Chances are that if youve neglected a spring checkup, your air conditioner
isnt cooling nearly as well as it could.A years worth of dirt and debris
clogging the cooling fins, a low coolant level, a dirty blower fan filter and a
number of other simple problems can significantly reduce the efficiency of your
air conditioner and wear it out faster.
You cant do everything; only a pro can check the coolant level. But you can
easily handle most of the routine cleaning chores and save the extra $120 that
it would cost to have a pro do them.
In this article, well show you how to clean the outdoor unit (called the
condenser) and the accessible parts of the indoor unit (called the evaporator).
All the steps are simple and straightforward and will take you only a few hours
total. You dont need any special skills, tools or experience. If you arent
familiar with air conditioners and furnaces/blowers, dont worry. Well walk
you through the basics. See Parts of a Central Air Conditioner, p. 107, to
become familiar with how an air conditioner works and the parts of the system.
You may have a different type of central air conditioner than we show herea
heat pump system, for example, or a unit mounted horizontally in the attic.
However, you can still carry out most maintenance procedures we show here,
because each system will have a condenser outside and an evaporator inside. Use
the owners manual for your particular model to help navigate around any
differences from the one we show in our photos. And call in a pro every two or
three years to check electrical parts and the coolant level ($150).
TIP
Call for service before the first heat wave, when the pros become swamped with
repair calls!
Cleaning the condenser
Clean your outdoor unit on a day thats at least 60 degrees F. Thats about the
minimum temperature at which you can test your air conditioner to make sure
its working. The condenser usually sits in an inconspicuous spot next to your
house. Youll see two copper tubes running to it, one bare and the other
encased in a foam sleeve. If you have a heat pump, both tubes will be covered
by foam sleeves.
Your primary job here is to clean the condenser fins, which are fine metallic
blades that surround the unit. They get dirty because a central fan sucks air
through them, pulling in dust, dead leaves, dead grass and the worst
culpritfloating cotton from cottonwood trees and dandelions. The debris
blocks the airflow and reduces the units cooling ability.
A typical central air conditioning system
Figure A Parts of a central air conditioner
Click Image to enlarge.
The outside unit, called the condenser, contains a compressor, cooling fins and
tubes and a fan. The fan sucks air through the fins and cools a special
coolant, which the compressor then pumps into the house to the evaporator
through a copper tube.
The coolant chills the fins and tubes of the evaporator. Warm air drawn from
the house by the blower passes through the evaporator and is cooled and blown
through ducts to the rooms in the house. The evaporator dehumidifies the air as
it cools it, and the resulting condensation drains off to a floor drain through
a tube. The blower unit and ducting system vary considerably depending on
whether you have a furnace (shown), a heat pump or some other arrangement. It
may be located in the basement, garage, furnace room or attic.
Always begin by shutting off the electrical power to the unit. Normally youll
find a shutoff nearby. It may be a switch in a box, a pull lever or a fuse
block that you pull out (Photo 1). Look for the on-off markings.
Vacuum the fins clean with a soft brush (Photo 2); theyre fragile and easily
bent or crushed. On many units youll have to unscrew and lift off a metal box
to get at them. Check your owners manual for directions and lift off the box
carefully to avoid bumping the fins. Occasionally youll find fins that have
been bent. You can buy a special set of fin combs ($10 at an appliance parts
store) to straighten them. Minor straightening can be done with a blunt dinner
knife (Photo 3). If large areas of fins are crushed, have a pro straighten them
during a routine service call.
Then unscrew the fan to gain access to the interior of the condenser. You cant
completely remove it because its wiring is connected to the unit. Depending on
how much play the wires give you, you might need a helper to hold it while you
vacuum debris from the inside. (Sometimes mice like to over-winter there!)
After you hose off the fins (Photo 5), check the fan motor for lubrication
ports. Most newer motors have sealed bearings (ours did) and cant be
lubricated. Check your owners manual to be sure. If you find ports, add five
drops of electric motor oil ($5 at hardware stores or appliance parts stores).
Dont use penetrating oil or all-purpose oil. Theyre not designed for
long-term lubrication and can actually harm the bearings.
If you have an old air conditioner, you might have a beltdriven compressor in
the bottom of the unit. Look for lubrication ports on this as well. The
compressors on newer air conditioners are completely enclosed and wont need
lubrication (Figure A).
Restarting procedure
In most cases, you can simply restore power to the outside unit and move inside
to finish the maintenance. However, the compressors are surprisingly fragile
and some require special start-up procedures under two conditions. (Others have
built-in electronic controls that handle the start-up, but unless you know that
yours has these controls, follow these procedures.)
1.. If the power to your unit has been off for more than four hours:
a.. Move the switch from cool to off at your inside thermostat.
b.. Turn the power back on and let the unit sit for 24 hours. (The
compressor has a heating element that warms the internal lubricant.)
c.. Switch the thermostat back to cool.
2.. If you switched the unit off while the compressor was running:
a.. Wait at least five minutes before switching it back on. (The compressor
needs to decompress before restarting.)
With the air conditioner running, make sure its actually working by touching
the coolant tubes (Photo 6). This is a crude test. Only a pro with proper
instruments can tell if the coolant is at the level for peak efficiency. But
keep a sharp eye out for dark drip marks on the bottom of the case and beneath
the tube joints. This indicates an oil leak and a potential coolant leak as
well. Call in a pro if you spot this problem. Dont tighten a joint to try to
stop a leak yourself. Overtightening can make the problem worse.
Clean the indoor unit
The evaporator usually sits in an inaccessible spot inside a metal duct
downstream from the blower (Figure A). If you can get to it, gently vacuum its
fins (from the blower side) with a soft brush as you did with the condenser.
However, the best way to keep it clean is to keep the air-stream from the
blower clean. This means annually vacuuming out the blower compartment and
changing the filter whenever its dirty (Photos 7 and 8).
Begin by turning off the power to the furnace or blower. Usually youll find a
simple toggle switch nearby in a metal box (Photo 7); otherwise turn the power
off at the main panel. If you have trouble opening the blower unit or finding
the filter, check your owners manual for help. The manual will also list the
filter type, but if its your first time, take the old one with you when buying
a new one to make sure you get the right size. Be sure to keep the power to the
blower off whenever you remove the filter. Otherwise youll blow dust into the
evaporator fins.
The manual will also tell you where to find the oil ports on the blower, if it
has any. The blower compartments on newer furnaces and heat pumps are so tight
that you often cant lubricate the blower without removing it. If thats the
case, have a pro do it during a routine maintenance checkup.
The evaporator fins dehumidify the air as they cool it, so youll find a tube
to drain the condensation. The water collects in a pan and drains out the side
(Figure A). Most tubes are flexible plastic and are easy to pull off and clean
(Photos 9 and 10). But if theyre rigid plastic, youll probably have to
unscrew or cut off with a saw to check. Reglue rigid tubes using a coupling, or
replace them with flexible plastic tubes.
1. Turn off the electrical power to the condenser unit at the outdoor shutoff.
Either pull out a block or move a switch to the off position. If uncertain,
turn off the power to the AC at the main electrical panel.
2. Vacuum grass clippings, leaves and other debris from the exterior fins with
a soft brush attachment. Clear away all bushes, weeds and grass within 2 ft. of
the condenser.
Click Image to enlarge.
3. Realign bent or crushed fins with gentle pressure from a dinner knife. Dont
insert the knife more than 1/2 in.
4. Unscrew the top grille. Lift out the fan and carefully set it aside without
stressing the electrical wires. Pull out any leaves and wipe the interior
surfaces clean with a damp cloth.
5. Spray the fins using moderate water pressure from a hose nozzle. Direct the
spray from the inside out. Reinstall the fan.
6. Turn the power back on, then set the house thermostat to cool so the
compressor comes on. After 10 minutes, feel the insulated tube. It should feel
cool. The uninsulated tube should feel warm.
7. Turn off the power to the furnace at a nearby switch or at the main panel.
Then pull out the furnace filter and check it for dirt buildup. Change it if
necessary.
8. Open the blower compartment and vacuum up the dust. Check the motor for
lubrication ports. If it has them, squeeze five drops of electric motor oil
into each.
9. Pull off the plastic condensation drain tube and check it for algae growth.
Clean it by pouring a bleach/ water solution (1:16 ratio) through the tube to
flush the line. Or simply replace the tube.
10. Poke a pipe cleaner into the drain port and clean out any debris. Reinstall
the drain tube and turn the power back on.
>From The Family Handyman - April 2005
[Non-text portions of this message have been removed]
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