If your air conditioning system is not working properly, use the information below to narrow down the troubleshooting process and help the service technician zero in on the most likely causes.
Why is it important to maintain clean air ducts? (click to expand & close)
Duct cleaning focuses on various heating and cooling system components of forced air systems. These include the supply and return air ducts, registers, grills, diffusers, cooling coils, condensate pan, fan motor, blower wheel housing, and the inside of the air handler cabinet.
If the AC system is not properly installed, maintained, and operated, the internal components may become contaminated with particles of dust, pollen or other debris. If moisture is present, the potential for microbiological growth (mold) is increased, and spores from such growth may be released into the home's conditioned space. Some of these contaminants may cause allergic reactions if occupants are exposed to them.
All of the components of an air conditioning system that come in contact with the air stream must be cleaned and decontaminated. Failure to clean a component of a contaminated system can result in recontamination of the entire system, negating any potential benefit.
Always use a company that is qualified to perform the complete job and has the credentials and track record to prove it.
Duct cleaning services will typically use specialized tools to dislodge dirt and other debris in duct work coupled with a high-powered vacuum to draw out all the contaminants.
Duct cleaning services may propose applying chemical biocides designed to kill microbiological contaminants to the inside of the duct work and other system components. Such services may suggest applying chemical treatments, sealants or other encapsulants to seal or cover the inside surface of the air ducts, metal parts, and cabinet interior insulation. The idea behind the sealants is to control mold growth or prevent the release any dirt particles and fibers from air ducts.
What to expect when duct cleaning.
Open all access panels to allow the entire system to be cleaned and inspected. Use vacuum equipment that exhausts particles outside of the home. Use only high efficiency particle air ( HEPA) vacuuming equipment if the vacuum exhaust is inside the home.
Protect the carpet and household furnishings. Use well-controlled brushing of duct surfaces in conjunction with contact vacuum cleaning to dislodge dust and other particles. Use only soft-bristled brushes for fiberglass duct board and sheet metal ducts that are internally lined with fiber glass.
Seal and reinsulate any access holes airtight.
You should not be able to detect any debris inside the duct work with the naked eye.
Keep your ducts clean.
Use a good efficiency air filter recommended by your AC contractor and change it every 30 days. If your filter becomes clogged, change them more frequently.
Make sure the air cannot bypass the filter through gaps around the filter holder. Keep the coils clean through proper maintenance. Do not operate the AC unit during any construction or renovation.
Vacuum your home regularly using a high-efficiency HEPA or highest vacuum filter bags. Vacuuming greatly increases the amount of dust in the air, during and after.
What is an indoor coil? (click to expand & close)
Indoor Coil (Heat Pumps) or Evaporator (Air Conditioning ) is located inside of the air handler or packaged unit. It's sometimes a little difficult to access, which makes it is one of the most neglected parts.
The indoor coils will act like a magnet to anything in the air stream that gets past the filter. It sweats constantly from the humidity in the air condensing on its tubes and fins. Because of this moisture, anything in the air that can be drawn in by the blower, including pollen, household dust, dust mite debris, mold spores, lint, pet dander, bacteria, and particles that can carry viruses, will become lodged in the internal parts of your AC system including the indoor coil. The indoor coil is the perfect environment for anything alive in the air because it is provides water, cool temperatures, dust and darkness. This promotes algae and mold growth, which degrades indoor air quality.
Poor indoor coil maintenance will allow the buildup of solids in between the fins and where the air enters the coil. The indoor or evaporator coil acts as a heat transfer medium allowing the heat energy from the air to be transferred to the refrigerant inside the coil. As the device used to transfer this energy, if the coil is insulated by dirt, algae, mold or anything else that floats in the air, the heat transfer process will be greatly reduced and the energy that you are paying for to produce refrigeration will be wasted.
The indoor coil sits on top of the drain pan allowing gravity to pull the condensate water off the coil and collect in the drain pan to be directed to the primary drain outlet.
The best solution to a dirty indoor coil or evaporator is to have the coils removed and cleaned by a professional AC company. You can keep it clean going forward with regular maintenance and good quality air filters.
If your AC runs, but emits a moldy smell from the supply air vents during operation, you could have a dirty indoor coil and / or primary condensate pan. If your return duct is in the attic, check it for leaks.
Black dust particles come out of the supply air vents during operation. They can cause a dirty blower wheel and/or dirty duct work.
Outside Units 101 (click to expand & close)
An outside unit (condensing unit) must have at least 12 inches of clearance from buildings or shrubs. Remove or avoid any obstructions that would restrict proper airflow or inhibit servicing of your equipment. Access to service panels on the unit must be clear out to at least 30 inches for ease of service.
Any vegetation at all around the outside unit (condensing unit or packaged unit) should be trimmed and kept clear of the unit. Do not build any structure that restricts the airflow in from the sides and out through the top or side. Restricting or blocking off this air flow will greatly reduce capacity and efficiency, and possibly trip sensors that protect the equipment from malfunctioning. The areas above the outdoor units that have top discharge for their outlet should maintain a clearance of about five feet or more. Always check with the manufacturer of your specific unit for their recommendations.
Outside units should be installed on a leveled platform that isn't cracked, rusting, loose, or otherwise impaired. Your outdoor equipment should be strapped and fastened to this platform securely to resist being blown away in case of a severe wind storm.
Outdoor unit coil cleanings should be performed by a qualified AC company. Clean dirt, leaves and any other debris that accumulates in the bottom of your outdoor unit. Outdoor coils sometimes look clean but in reality can be very dirty. This coil cleaning allows for better heat transfer, which makes the air conditioning unit work more efficiently.
Tip: On outdoor units with exposed coils, put some decorative blocks about six inches high around the perimeter of your unit to protect it from weed-wackers. This will protect the coil fins from being flattened and prevent the loss of efficiency, as well as a potential refrigerant leak.
Keep the sprinkler heads pointing away from your outdoor unit. Sometimes ground water can have minerals that cause premature corrosion to metal parts.
If your unit sits in an area of the yard where the rain runoff pours into its fan outlet, it may be a good idea to put a rain diverter on your roof or gutter to redirect the water away from your unit. Some naturally falling rain water is harmless, but not a heavy down poor directly into the fan area. This will shorten the life of the fan motor.
AC Maintenance 101 (click to expand & close)
The primary condensate drain is where the water from your unit exits. This water or condensate is the product of the humidity in the air condensing on the indoor coil and dripping onto the drain pan. This is the moisture that is removed from the air that is being conditioned and cooled by your indoor coil.
If a clog were to occur in the primary drain outlet or in the pan itself, the water level in the drain pan will rise and reach the level of the secondary outlet where there should be a device to detect the water rising and turn off the AC unit. This secondary outlet can also be piped and drained to a location where the occupant can see it and detect the problem.
Secondary drains are also sometimes called "emergency drain pans" or "auxiliary drain pans."
Air handlers in the attic will always have an auxiliary drain pan under them to catch the sweat on the surface of the air handler and the overflow condensate in a primary drain stoppage.
All auxiliary drain pans must have a condensate overflow switch attached to the side of the pan that will automatically shut down the air conditioner in an emergency overflow situation. This water/condensate will have to be removed from the auxiliary pan when the clogged primary drain is cleared. There are many types of float switches available.
The condensate drain line will allow the water that is accumulated in the primary drain pan to drain toward an area outside the home. This drain line is typically a ¾ inch plastic pipe or PVC. When this drain pipe goes without maintenance, the condensate or water will not flow through it efficiently. As a result, an overflow can occur into the ceilings , walls or other parts of your home and cause water damage.
Standing water is the perfect breeding ground for algae and mold!
A properly functioning condensate overflow switch will shut down your AC unit to avoid property damage and let you know there is a problem.
Homeowners should know where the location of the condensate drain line outlet is in their home.
Sometimes it is located next to the outdoor unit. Make note of the location in case you have to deal with an emergency water leak caused by the AC.
If a leak should occur, use a wet/dry vacuum and slide the inlet hose over the outlet of the condensate line. Use a wet rag if you need to make a good seal and with the suction part of the vacuum let it run for a few minutes to dislodge the algae in the drain line and avoid any further water damage. This can get your AC back working until you can get a technician to inspect your unit or have it cleaned properly. After you finish, the water will not come out immediately – it takes some time to start dripping when you are done vacuuming. Some drains are very long, others run underground and need to collect condensate water in them to start to drain out. On a dry day it can take even longer to drain any water.
After your AC unit has been cleaned or inspected and the drain pan and line are working as designed, the next thing to do is to install some type of approved algaecide. Household bleach is good, but be aware that bleach is corrosive to metal parts and will stain and damage property if no used properly.
The safest aproach is to have your contractor install a Tee fitting to your primary drain line to install the bleach.
All primary drain lines located in non air-conditioned space will need to be insulated so that they do not sweat and cause stains below the drain lines. This is essential because the drain line has cool water flowing through it. This cool temperature will transfer to the outside of the drain pipe and sweat on the surface if located in the attic or garage for example.
All drain lines should be pitched slightly downhill going away from the air handler primary drain outlet where it exits the unit in the attic, closet or garage to the area it is going to drain. You should not have any sags where the water will settle or accumulate. This can cause algae to form and block the flow of water to the outside. A properly supported drain line at the right intervals will avoid this from happening.
Always keep the condensate line outlet clear of mulch, dirt and vegetation. This will keep the drain line unrestricted and flowly freely.
Algae tablets can be installed by the homeowner in the primary drain pan. When these tablets dissolve, a steady stream of algae-preventing solution will flow into the drain line. Just ask your service technician how to place the tablets in the pan.
All condensate pumps have a float safety shut off switch. In the event of a pump failure, or a plugged or kinked outlet line coming off the pump discharge, this float safety switch will shut down the air conditioning system and water will not overflow and cause damage.
The condensate pump is very important. The pump sump will promote algae growth if not cleaned at least once a year.
The condensate pump outlet line is a nylon or copper material and must be flushed at least yearly to prevent the buildup of lime or other deposits.
Algae tablets can be added to the condensate pump sump also at least every three months.
Why does my air conditioner leak water? (click to expand & close)
When solids accumulate in the drain line
they eventually obstruct the flow of condensate water.
Typical solids in the drain line include
algae, dirt, rust, slime, dried PVC solvent, plaster
dust mixed with water, saw dust, and more.
All drain lines should be serviced at least
once a year to avoid the potential for water damage to the area beneath
the air handler or packaged unit.
Drain lines are cleaned either by applying
high pressure water or air at the exit of the air handler drain in the direction
away from the air handler, or with a wet/dry vacuum
to suction the outlet which is located outside the home.
Gravity drain lines
there must be at an angle of at least 1/8 inch per foot so that the water in
the line will travel away from the air handler.
Drain line backup is one of the most common problems
relating to air conditioning with a poor service
After the drain lines are clear and clean you can keep them clean by pouring about a drinking glass full
of household bleach into the drain line as close as possible to the drain
outlet at least twice a year.
There should be a PVC fitting called a "clean
out" fitting with a slip cap. This aids in
maintenance by homeowners enabling them to pour the household bleach and
replace the cap when finished.
A wet/dry vacuum cleaner is used to
suction the outlet of the drain system, which is usually located near the
condensing unit or the outside wall close to the air handler. Connect the
suction part of the vacuum cleaner to the drain outlet and let it suck for
about two minutes. This will clear any solids in the drain and allow the drain
system to flow freely again.
Air handler drain pans sometimes have a device called a condensate overflow float switch or safety float
switch. If you look at the air handler drain pan you will see two, sometimes
three threaded holes.
One will always be used as the main primary drain, which will tap one
hole and go directly to the outside to drain. If the primary drain line or
outlet becomes blocked and stops draining, the condensate water will start to
flow out of the secondary drain threaded hole. At that point, the condensate
float switch or safety float switch will start to fill up and a float device or
water sensing device will shut down either the complete
AC unit or the condensing unit that produces the water. The sole purpose of
this device is to prevent water damage to anything directly below the air
The condensate overflow float switch or safety float switch can be wired in two ways. The first and best would be to only shut down the condensing unit in the event
of a drain line blockage. In this case, the condensing unit or outside unit
will shut down and will allow the air handler to continue to run and allow the
blower to circulate non-cooled air until the problem is diagnosed. The second
wiring option is for the float switch to disable the entire system until a
proper diagnostic is performed.
On very hot and humid or rainy days, a poorly-maintained AC drain will be working at maximum
capacity. This can cause a backup and lead to water damage below the air
handler or packaged unit.
Condensate pumps have a condensate
overflow float built in. This allows the complete system or the condensing unit
to shut down when the pump isn't able to remove the water from its sump, preventing
the water from overflowing and causing damage.
Condensate pumps have an outlet nipple with a
hose or tubing attached to it that direct pumped water to a place where
it will not cause damage or a safety hazard. This hose or tubing has to be
flushed periodically or it will build up deposits that will restrict the proper
A dirty coil is a sure sign of a drain
line about to become clogged.
The technician cleaning your coil should
also clean the draining system as part of the coil cleaning job.
There should only be one P-trap installed per
air handler or packaged unit to avoid an air lock between both P-traps
and prevent the free flow of water out of the drain.
The technician cleaning our coil should
remove the drain pan from the coil to insure all accumulations of solids are
removed between the drain pan and coil.
Why is my air conditioner frozen? (click to expand & close)
Definition: Indoor coil (evaporator) is the part
inside the air hander that does the work of absorbing the heat inside your air conditioned area and removing the hidden heat which is
the humidity from the air.
Frozen indoor coils are a result of the accumulation of anything that can float in the
air and go around the air filter to end up lodged in the surface area or inside
the metal fins. This accumulation acts to insulate heat from being absorbed
into the indoor coil leading to its freezing.
A dirty air filter restricts the air flow
just enough to choke the indoor coil. This prevents it from doing its primary
job which is to absorb the heat and keep the surface temperature from dipping
below 32 degrees and freezing any water on its surface.
This ice, in turn, acts as an insulator from heat being absorbed into the
A refrigerant leak will cause the refrigerant pressure
to dip below the safe minimum and drop the surface temperature of the indoor
coil below the 32 degree limit. Freezing will occur
immediately, even with a clean coil and filter. If it runs long enough, the ice
will build beyond he drain pan and will melt and leak water.
Some refrigerant leaks can be found by a visual inspection of any
cooper, aluminum, brass, or steel parts.
They typically will have a very light oil residue.
Refrigerant leaks will need to be diagnosed by an AC professional.
If you see any ice
or water during inspection of your air handler, you could have a refrigerant leak in the system. This means that your
system is working at a very low capacity. Refrigerant leaks must be
repaired before any lost refrigerant is added back into the system.
How to inspect
for an iced up air handler coil
For a closet air handler, remove the air filter and get
under the air handler with a flashlight. Look straight up to spot any evident
of ice. The cooper tube exiting the air handler (the one with the soft
insulation) also needs to be peeled back.
If you see any ice, or there's no ice but the copper tubing is at room
temperature, these are signs of frozen coils or a refrigerant leak. If you
change your filter at a grill that means that your return is ducted. Check the
copper lines inside and outside the house for any ice.
thermostat fan setting to ON, and
the mode setting to OFF. This will stop the refrigeration and allow the indoor
fan to thaw the ice off the indoor coil. Depending on how much ice is
accumulated on the coil, it can take from one to two hours. The thermostat setting will allow the blower to circulate air
throughout the home or the coil to thaw while the technician comes to diagnose
the problem. The other option would be to shut down the whole AC system. You
can also check the coils or feel the supply air vents for the proper amount of air flow. Water may spill, so take precautions to absorb it.
You can check to see if
the air handler blower is running just by
standing next to it and listening for the sound of air flowing. See if you feel
any air entering the return grill or exiting the supply grills in the ceiling
or walls. If there's no sound, it means the blower motor is not working as it should.
Why isn't the air blowing cold from the outlets? (click to expand & close)
Check the inlet and outlet temperature of your system with a
thermometer. First, turn your thermostat to cool and let it run for at least 15
minutes. The preferred outdoor temperature needs to be at least 70 degrees.
Take a temperature reading at the return grill where your clean filter
is installed. Keep it in the air stream for at least two minutes. Record the
temperature. Next, place the thermometer in the air stream of the cold air
supply grill closest to the air handler for at least two minutes. Record the
temperature. Now subtract the first reading from the second.
As a rule of thumb, 15-20 degrees is an acceptable temperature
difference. A large deviation from the 15-20 range could mean the system is not
Common AC terms. (click to expand & close)
Drain line: The plastic PVC pipe or
copper pipe used to divert condensate water away from the air handler to a
place where it will not be a nuisance.
Gravity drain system: A system where the
water in the AC drain line is propelled by gravity all
the way to an outdoor location. The air handler drain exit will always be the
highest point of the drain line.
Forced drain system (pumped): The air
handler drains by gravity directly into the sump tank of a condensate pump at
short distance. The pump will increase the pressure of the water so that it can
go in any direction needed, even strait up across and down. This option is
usually used where gravity drain is not feasible. This pump needs periodic maintenance to
clear out any algae growth inside.
P-Trap: A device installed in the drain
line that acts as an air seal by stopping the vacuum being generated in the line
and allowing the condensate water to travel out and away from the air handler.
All drain lines must have a P-Trap. They are located next to the air handler,
outside next to the wall, or under the foundation and exiting vertically from
the ground outside.
Air handler (indoor unit): Air handlers have a built in fan that acts as the air pump
for the entire indoor zone that it conditions. In the cooling season, the air
handler's built-in indoor coil will get cold
enough to lower the temperature and dehumidify the air that flows through it.
In the heating season, the heating strips will
get hot enough that it will raise the temperature of the air flowing through
the heating elements to supplement the heat loss of the home. Air handlers
feature vertical or horizontal flow and can be located in a closet inside or
outside the home, in the garage on a return air box, or horizontal on a loft. They
can also be in the attic, horizontal on a trapeze support system. The air
handler's main components are the indoor coil, blower section, heat strips, or
Condensing unit (outdoor unit): Located
either at ground level next to the house or on a roof top, this unit has three
main components: the compressor, condenser coil, and the fan motor.The compressor is the pump that circulates refrigerant
through the refrigeration circuit. Throughout the lifespan of your AC system, the
compressor will have used the most amount of electricity in the average home
compared to any other energy-consuming appliance. That's why it is important to
select the most efficient system. The condenser coil
is the most exposed part of the condensing unit. As the condenser fan draws
ambient air through the condenser coils, the vapor refrigerant cools and
changes its property to a liquid.
Drain pan: Located directly below the
indoor coil, the drain pan catches all of the condensate water runoff by
gravity. This dripping will occur only when in the cooling mode. The drain pan
will direct all of the water to its primary outlet which is treaded fitting
made of plastic PVC pipe.
Condensate water: Water that comes from
the humidity in the air, also known as latent heat or hidden heat. It forms on
the evaporator coil when its temperature falls below the dew point of the indoor air.
Variable speed air handlers: Air
handlers where the blower motor changes its speed depending on the features or
settings. This allows the installer to set the blower speed according to the
owners needs or preferences and allows for the best humidity removal and most quiet
Air filters 101 (click to expand & close)
Filter and Maintenance Knowledge.
Don't forget to
change your air filter!
Poor filter maintenance is the culprit behind three areas of
Dirty air filters make your AC unit work very hard and at a
longer rate of time, causing more energy to be consumed. The more energy it
consumes, the higher your home energy bills go. Basic filter maintenance will
help keep energy usage to a minimum.
A dirty air filter of any type may result in extensive
damage to the fan blower motor or more frequent cleanings of the internal parts
of your air handler. Dirt and grime that accumulate on crucial moving parts can
cause them to fail much quicker than normal. This can be very costly and
sometimes lead to a total system replacement. At the very least, your system's
life expectancy will be significantly reduced.
Most importantly, neglecting to change your air filter
regularly can cause potential health problems.
Your filter is the primary defense against harmful airborne
allergens and contaminants. A quality home air filter changed on a regular
schedule is a small investment to protect your family's health.
The only economical way to improve indoor air quality is by
controlling the flow of pollutants and allergy-causing irritants. Firs, choose a good quality rated filter. Second, make sure
the filter size dimensions (width, length and depth) are the ones your unit is
designed to work with.
Air filters too low in efficiency will allow
contaminants to continue their flow through the filter and stick to every
internal component of your air conditioning system. This will reduce
efficiency, capacity, and eventually, trigger a downward spiral of more
Air filters too high in efficiency will restrict the
hot and humid air from entering the air conditioning system to be processed for
comfort cooling and dry dusty air for heating.
are the most hygienic. You throw the whole filter away replace it with a fresh
one every month. No frames or screens are left behind to continue collecting
Signs of using poor quality filters and extending the
replacement past 30 days include:
- Having to acid wash the AC coils more frequently than 3-5 years.
- The Drain line and condensate pan backs up and leaks water more
- The blower wheel
(which is the fan) produces a lower quantity of air, reducing
- Air ducts build up contaminants which can
be seen exiting supply air grills and diffusers.
- Dust settles on furniture throughout the conditioned space.
Carpeted air conditioned
spaces require even more attention to filters and maintenance. Rugs and carpets
tend to hold dust and other debris until you walk on them and it becomes airborne
and drawn into the air handler.
Filters in a grill located in the ceiling or walls
have a duct leading to the air handler. If this duct has any leaks, unfiltered
air will enter the return air leading to the air handler causing it to accumulate
contaminants that induce premature failure.
Minimum Efficiency Reporting Value, commonly known as
MERV Rating, is a measurement scale designed in 1987 by the American Society of
Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) to rate the
effectiveness of air filters.
MERV 7-8 recommended typical residential and
commercial application: Pleated
filters - disposable extended surface area, cotton polyester blend media with
card board frame having 90+% efficiency.
Filter Sizes: Nominal
Nominal Dimensions – the size
of the housing slot or bay where the filter is installed into – usually
differ from the exact or Actual Dimensions. The Actual Dimensions of the filter
can vary in length and width from ¼" to ½" smaller than the
Nominal Dimensions or the printed label on the filter. Always measure the exact
size of the slot or bay where the filter is installed (length and width). Next,
subtract from the length and width ½" respectively to come up with the
exact custom filter dimensions to order. This size will also be useful for
finding the equivalent size of your filter.
Example: If you measure your current filter as 19 ½" X 23
½", your housing slot for your filter to slide or be placed into should
measure 20" X 24".
Reverse Example: If you measure the housing slot of your air
handler, or the inside of the return grill where the filter is installed, and
it measures 20" x 24" nominal, then the actual size filter you need to buy is
19 ½" x 23 ½".
Electrical Trouble? (click to expand & close)
Warning: If you are not
comfortable working with high voltage equipment, please consult with a
Go to the main circuit breaker panel and check for any breaker that is
in-between the on and off position and feels loose. If found, switch the breaker
to the off position and then to on. Next, search on the bottom and sides of a
closet air handler and check for any breaker that has tripped in the
same way. Remember: Tripped breakers will feel loose in the middle position.
Move them toward the off position and then on.
If the breaker will not stay on, or a replaced fuse keeps blowing,
schedule a service call to further diagnose the problem. Always remember
to replace a fuse with one of the same size.
A recurring tripped breaker or blown fuse is a defense mechanism to
protect the circuit wiring and the air conditioning components from sever
damage. They are designed to stop the flow of current to any electrical device
when it is over-currented, short-circuited, or
Also, around the outside unit, you will find a box containing either
a pull switch (make sure it is making good contact by pulling and reinserting
it), a circuit breaker (check to see if it is tripped), or a combination fuse
holder / pull switch. Make sure the fuses are new. If they're not, replace them with the same
size and reinsert.
Why is my electric bill so high? (click to expand & close)
If your air conditioner starts running much
more frequently, check the air filter. In the South Florida heat, air
conditioners run more than usual and a fresh filter should be installed every
three to four weeks.
With the filter out, look straight up into
the air handler with a flashlight and inspect your coil for any signs of
accumulated dirt, dust, water, or a musty smell. These are indications of a
dirty indoor coil. Dirty indoor coils are the
most common problem relating to air conditioning and the biggest cause of
Inefficient split central AC system
With the unit in the cooling mode and operating, go outside and touch the small
cooper tubing (liquid line) exiting the outdoor
unit. If it is between warm to hot to the touch, the outdoor coil is either
dirty or the aluminum that the coil is made from has lost all of its heat
transfer properties and is not removing the heat from the refrigerant inside
the tube you touched.
Inefficient split central ac system
With the unit in the cooling mode and operating, go outside and touch the
larger cooper tubing (suction line) usually
covered with an insulation. If it is very cold and if you can look inside and
are capable of seeing the compressor exposed with a flash
light, focus on the surface of the compressor. Check to see if it looks
like it is drenched in sweat or if the cement support under the outdoor unit is
wet or moist. These are signs of a dirty indoor coil, dirty air filter, or too
much refrigerant in the system.
Air ducts located in the attic, soffit,
partitions, and any area that is not in the air conditioned space, is leaking
air out and not using this cold air for the inside of the home where it is
needed. This leaking air to the outside causes the home to suck hot humid air
from the outside through all of the doors, windows, fixtures, and receptacles.
Split central AC system: In the closet where the supply air duct penetrates the ceiling, there must be an air
tight seal between the duct and ceiling on all four sides, including the back,
which is the least visible and most neglected. Use a small mirror with a
telescoping handle and check it. Dust on the air handler surroundings could
indicate this problem.
Check the inside walls of the closet to
make sure there is no interruption between the ceiling and the floor. Confirm
if there are cracks, openings, missing plaster or any signs that air can be
pulled from the attic through the wall cavity into the closet, and then into
the air handler air flow. This hot, humid, dirty air puts
more load on the AC, the filter gets dirty more
frequently, and your coil will get dirtier sooner than later. Dust on the air
handler surroundings could indicate this problem.
Proper attic ventilation, both
mechanical and natural, are very important. Attics can
get to temperatures of up to 120 to 130 degrees in the summer. This heat can
radiate through the ceiling into your home and add load to the conditioned
Attic ventilation typically will have an
intake through the eaves, and discharge the hot attic air through the highest
part of the roof.
An attic environment hotter than 120 degrees will start to effect the
ducts by increasing the rate at which the heat travels through the duct insulation outer wall material and effect the
cold air traveling though them.
Air ducts can leak the internal air you have paid for to cool, dehumidify
heat, and filter. A rate of 5% is fair, but larger leaks can diminish the
capacity of some parts of your home.
Duct leaks can be located in several places, including at joints,
couplings, seams, and connections.
Homeowner Tips (click to expand & close)
Pay attention to changes in your comfort system and report
them to your AC maintenance company. New patterns such as higher than normal
electric bills or your AC system making a different sound while operating, may
be warning signs of potential problems. Catch these problems early and you're
more likely to avoid costly repairs.
It pays to know where your outside unit is located. If you
live in an apartment, townhouse or condo, make sure the unit is clearly marked
with your unit number. That way your service company will not have to spend time
looking for it. This also prevents other service companies from accidentally
working on your unit.
Turn off your comfort system during thunderstorms to prevent
the electric power from turning off and on suddenly and causing unwanted stress
on your AC unit.
Do not stack items on top or close to the outdoor section of
your AC unit or have plants up against it. You should not restrict the airflow
into or out of the unit. Air flow restriction will cause loss of efficiency and
could result in damage to your unit.
Ductwork may be the source of lost AC efficiency. This is
due to leakage of the conditioned air escaping into your attic through the
cracks or seams in the duct system. Often the foil tape used to fabricate the
ducts becomes loose and allows air to escape. Have your duct system checked for
leaks. Any time a cable, alarm or other contractor enters the attic, there is a
potential for damaged duct work.
Proper attic ventilation and insulation will help keep
electric bills down. Attics can get to temperatures of 120 to 130 degrees in
the summer. This heat can radiate through the ceiling into your home. The AC
must work harder to remove this heat, causing higher utility bills.
Air ducts in your home need to be cleaned if you notice
substantial mold growth inside hard surfaces. Take a flash light and look
through your supply air vents for mold growth. Remember, if the conditions
causing the mold growth in the first place are not corrected, it will continue
If the lights in your home dim when the AC unit starts, you
should have the system checked for proper operation. If this does not resolve
the problem, have the electrical circuit breakers and main panel checked by an electrician.
The final check should be of the electrical meter and electric meter socket
where the main power enters your home.
How do I change my air filter? (click to expand & close)
Changing Your AC
Locate the air filter which is usually as close to the
blower or air handler as possible. Check directly under the air handler or a
small door on the bottom of the air handler . Filters
are sometime located inside of a grill on the wall or ceiling. If you locate
the thermostat it should be in this area. It's usually in a central location.
Remove the old filter and place it in a bag to contain the
Take a fresh filter or clean the washed and dried filter and
install with the arrow pointing toward the air flow or blower. Record the date.
If you experience more dust levels in your home due to filtration from outside
air, you may need to change or wash your filter more frequently.
How often should I change my air filter? (click to expand & close)
The effectiveness of your filter depends on your environment
and the type of filter you have installed.
Factors to consider include:
- Number of people living in the home
- Pets in the house and frequency of shedding
- Smokers in the house
- Window or doors in the house leaking around the closures
- Pollen bearing trees or plants close by
- Living in an area with a lot of dampness around the home
- Habits of people living in the house, such as leaving doors open, going in and out frequently
If several of these factors sound familiar, you'll likely
experience a quicker loading of particles on your filters and will need to
change it more often. A good rule of thumb is to check every month.
A clean air filter will also prevent dust and dirt from
building up in the system and result in maintenance and utility bill savings.
Why is AC maintenance important? (click to expand & close)
Lack of AC maintenance always costs you money in the long run. When indoor and outdoor coils get dirty, they don't allow efficient heat transfer. This causes your system to run longer and work harder. Some components need adjustments or calibration. Loose or burnt wire connections can waste energy. Improper refrigerant charge and dirty filters can also have negative effects on your AC unit.
Poor maintenance could also be hazardous to your health and home. One example of a potential health problem could come from your indoor coils and primary condensate pan. If the coil and pan are not maintained, algae and mold could accumulate. Many people have allergic reactions to these irritants.
Most AC systems have an average life span of 12-20 years. Generally, lack of maintenance will shorten the life of your unit. A dirty, non-tuned system must run longer than a well-maintained system to do the same amount of work. As a result, you get less cooling for your dollar.
Not changing your air filter on a 30 day schedule is the number one reason for premature aging or mechanical failure of your comfort system.
Changing your air filter will save you money on your electricity bill. You can help keep your comfort system efficient and your home healthy with proper filter maintenance.
Mark your calendar, or remember to replace your filter when your electric bill comes in the mail or online.
What is MERV and why is the MERV rating important? (click to expand & close)
What does MERV mean?
What is MERV (Minimum Efficiency Reporting Value)?
This is a filter rating system devised by the American
Society of Heating, Refrigeration and Air Conditioning Engineers ( ASHRAE) to standardize air filter efficiency ratings to
the public. The higher the MERV rating, the higher the efficiency of the air
conditioning filter. By using a MERV 12 rated filter,
for example, you
will remove smaller particles from the air than a MERV 8 filter.
The purpose of this rating system is to help consumers
effectively compare one filter against another. Also, if one manufacturer's filter is rated MERV 8 and
another's is also MERV 8, they will
perform just about the same, respectively. Remember, the MERV rating only
applies to the efficiency element of the filter. Additions such as carbon,
antimicrobial treatments, baking soda, etc. are value added benefits and do not
have anything to do with the MERV rating system.
MERV 8 filters or higher are your
best protection against allergies or asthma.
MERV Ratings Explained
compare different companies using the same MERV rating. Some manufacturers have
their own rating system.
rating of 13 means the filter is 90% + efficient at filtering 3-10 micron sized
particles and capturing measured particles such as bacteria, tobacco smoke,
virus carriers and particles in a sneeze. This is a superior residential
MERV rating of 11 means the filter is 85% + efficient at filtering 3-10 micron
sized particles and capturing
measured particles such as microscopic allergens, lead dust, milled flour, auto
emissions and other fumes.
MERV rating of 8 means the filter is 70-85% efficient at filtering 3-10 micron
sized particles and capturing measured particles such as mold spores, dust
mites, dusting aids, cement dust and pet dander.
fiberglass throw-away filters are rated at a MERV 4 which is 20% or less
efficient at filtering 3-10 micron sized particles and capturing the measured
particles like pollen, sanding dust and larger dust particles like lint and
carpet fibers. This is considered minimal acceptable filtration capacity.
Why is my AC making strange noise? (click to expand & close)
A Whistling noise coming from the air
handler is usually the result of misaligned panels or missing screws. The
vacuum being created inside the air handler will draw air from the outside
through the openings on the air handler and make the sound.
Dirty filters will cause noise as air
rushes through the sides of the air filter.
Excessively high blower motor speed will
Too small of a return air grill will
The Louvers on the door to the air handler
closet can cause the air flowing through it to vibrate the louvers and make
noise. The high velocity is caused by too small of an in-between air gap for
the cubic feet of air flowing through.
A hammering noise can travel thru the
copper refrigerant lines originating at the compressor
and being amplified somewhere inside the home where the occupants will hear it.
The cause is a faulty compressor.
A hammering noise can also be heard if
the bare copper refrigerant lines are in contact with a
part of the structure of the home like the block wall or the cement
Sometimes copper lines will be in contact with other metal parts inside the condensing unit itself (outdoor unit ) causing noise to originate from this area.
If the blower wheel is off its centrifugal
balance, it will cause the whole air handler to vibrate causing noise. This will eventually also cause
damage by vibrating loose the welds to the indoor coil resulting in all or part
of the refrigerant being released from the system and a loss of cooling.
The outdoor unit fan blade assembly can
be off of its balance and vibrate or shake all of the covers and metal grills
that make up the outdoor unit assembly. This will cause a considerable amount
of noise to you and your neighbors.
The compressor will make a normal noise,
but sometimes you will hear a whining noise
louder than is acceptable by the manufacturer decibel ratings. This is a sign
that the internal components of the compressor are off of the manufacturer
tolerances. Usually the compressor will have to be replaced.
A restriction to the normal flow of refrigerant
will cause the compressor load to increase. Depending on the internal
mechanical conditions of the compressor, this will tend to increase the normal
noise it generates. Restrictions can be anywhere from a dirty liquid line
dryer, a kinked liquid line (small copper line),to a malfunctioning thermal expansion valve located next to the indoor
A gargling noise from the air handler
will come from the drain pan outlet. Not having a P-trap in the drain line
system will cause air to be sucked through the drain line. At the drain pan
outlet, where the condensate water is designed to exit, it will be splashed
back into the pan making a gargling noise.
A gargling noise from the copper refrigerant
lines will be caused by a low refrigerant charge causing this sound at
the air handler. This indicates a refrigerant leak or short of charge.
A spraying noise for less than a minute
after the air handler turns off is normal. Newer systems will have an internal
check valve built into the thermal expansion valve to eliminate this sound.
Thermostats 101 (click to expand & close)
If your thermostat takes batteries, make
sure they are new.
Set the thermostat to cooling mode and set your desired temperature
below the room temperature. Many systems have a delay
from 5-10 minutes before the outside unit or the air handler blower will
Relative humidity or % of humidity: This
refers to the content of moisture in the air. The lower the humidity % the
quicker the moister on your skin is evaporated into the air and you feel
cooler. Some thermostats will have a humidity gage on them to help you will see
the total picture.
The temperature reading on your
thermostat is the temperature your skin feels without taking into consideration
the humidity. So you're only getting half the information.
A programmable thermostats
is very good at saving you energy.
It will automatically turn your unit on and off, depending on the
First Setting: (Wake) would be while you are still at home sometime in
the early morning before leaving the house.
The thermostat will hold a temperature setting for (wake) amount of
time until the next setting.
Second Setting: (Leave) would be from the time you left the home in the
morning until you return which is the next setting. The thermostat will hold this
temperature setting which should be considerably
higher because the home shouldn't be occupied in this timespan. All you are
really interested in is keeping the homes temperature from going above 80
Third Setting: (Return) At this setting you would like the thermostat
to have the home at a comfortable temperature when you return to the house.
Fourth and last setting: (Sleep) Depending on your comfort level, you
have the option to have the programming adjust the temperature you sleep at until
the next morning or next setting which is Wake.
Thermostats should be installed at 5 feet
from the floor.
The location of a thermostat is where
all of the air from the zone that the air conditioning supplies is returned.
You would want that mix of temperatures from all of the areas to come together
and blow over the thermostat. This allows the temperature sensor built into it
to read the return air temperature and cycle the air conditioning according to
Never install a thermostat on a wall that faces
an exterior wall. This will give you a high reading in the summer, which
will make the cooling work excessively, or a low reading in the winter, which
will make the heat work extra hard.
Thermostat installation: Always seal the hole
made by the penetrating wire going to the thermostat. This will avoid erroneous
temperature readings caused by hot or cold air being pulled through the wall
cavity and coming into contact with the thermostat temperature sensor.
Digital thermostats are better at
detecting actual temperature in the occupied space and cycling on and off with
more precision. Some have an algorithm that allows for intelligent power usage.
On the other end of the spectrum, mechanical mercury bulb type thermostats,
which are very harmful to the environment if disposed of improperly, are not the optimal choice for saving energy. If in doubt,
ask the technician which one you have.
Installation of a thermostat should
include a system check. Switch to cool mode and lower the setting below the
space temperature to allow the thermostat time to cycle through the 5-10 minute
delay and turn on to produce cool air from the vents. Next, switch to heat mode
and raise the setting above the space temperature to allow the thermostat to
time to cycle down through the 5-10 minute delay and turn on to produce warm
air from the vents. Make sure the technician stays until this is checked.
How to prepare for the arrival of an HVAC service technician. (click to expand & close)
Preparing for the
service technician's arrival.
Iced up unit: Set the thermostat fan setting to ON, and the mode setting
to OFF. This will stop the refrigeration and let the indoor fan to thaw the ice
off the indoor coil. This will allow the technician to start the diagnostic
upon arrival. Water may spill, so take precautions to absorb it.
Service problem: Your unit is not frozen and does not cool. While
waiting for the technician to arrive, shut off the circuit breakers to the system.
This will prevent possible damage, which can occur if you allow it to try and
run or cycle on an off. In addition, if you have an overheated compressor or
fan motor and continue to leave the system running, it takes that much longer
for the components to cool down for proper diagnostic or startup.
Don't throw the most recent filter inside the unit
away. Let the technician inspect it and include it in the diagnostic.
Clear away anything that might be in the way of the air handler so the technician can easily open the
panels and conduct an inspection.
Clear away anything that can get in the way of the
technician having access to the condensing unit
(outdoor unit) or electrical disconnect, such as plants and shrubs.
Locate the main electrical panel to the entire home,
or that particular wing of the home, and inform the technician upon arrival.
Gather any paperwork that came with the unit when it was
installed that might aid in diagnosing the problem.
Put the dogs in a secure place as away from the yard and air
handler area as possible.
If the air handler is in the garage,
you will probable want to move anything from the garage that might obstruct access
to it, such as cars, furniture, supplies and materials.
If the air handler is
in the attic, locate the access hole to the attic
and clear anything that might interfere with placing a ladder under it.
Try to find all of the most recent invoices for any work done
to your air conditioning system. If possible, try to remember any comments made
by that the last technician to work on your system and write them down. The
more information you give the technician the faster the diagnostic and repair.
Find out where your drain line exits the house. It's usually next to the
condensing unit (outdoor unit) or the exterior wall that is closest to the air
Why do I need to change my air filter? (click to expand & close)
The air conditioning filter collects the dust, dirt, microscopic particles or anything else that floats or can be drawn into your unit. When the fan inside your unit turns on to distribute air, depending on the efficiency of what is installed, the filter will collect these particles to protect your system and clean your home's air.
When the filter is clean, it allows the maximum amount of quantity of air to flow through it and lets the AC unit work at its best efficiency. Once it has trapped a certain amount of particles, it starts to become ineffective and gradually restricts the air flow moving through the AC system. This requires the AC to work harder and longer to keep you cool or warm, wasting electricity and increasing your utility bills in the process. As air filters get dirtier, they become less effective at trapping the airborne contaminants and pollutants that irritate your breathing, triggering sneezing, allergic reactions and asthma. Always remember that you breathe what your inefficient filter or the overloaded filter can't handle any more.
A neglected and forgotten filter can build up so much dirt, that it can reduce the amount of air flow to the AC system causing a lot of problems to the homeowners. Besides the money wasted day after day, a worst case scenario could result in hundreds, if not thousands of dollars in repairs to the AC system.