Simple Tests to Check Air Conditioner
A window air conditioner is an appliance of considerable complexity that does not lend itself easily to do-it-yourself repairs. However, there is a good deal of maintenance that a homeowner can and should do to insure that an air conditioner is performing at its peak efficiency.
Air conditioners do four things: cool the air; remove moisture from the air; recirculate the air; and filter out dust. Needless to say, a free flow of air is absolutely essential. Anything that reduces this air flow around an air conditioner is going to adversely effect it.
A room air conditioner has two fans inside. One sits on the room side just behind the grill, filter and evaporator coils. This fan pulls the room air through the grill and filter, and across the cold coils, then blows it back into the room. In the process, the air deposits the dust in the filter, the heat is absorbed by the cold coils and the moisture condenses on the coils and then drips down to a collection trough.
The second fan sits in the back section of the air conditioner next to the condenser coils. This fan pulls air in through the sides of the unit and blows it out through the hot coils. This fan also picks up the water that collects in the bottom and slings it against the coils. The air and water cool off the hot condenser coils.
Filters are made of several different types of materials: foam, aluminum and fiberglass. They should be cleaned often or, in the case of fiberglass, replaced. The foam and aluminum filters are called permanent; however, after a few seasons the foam begins to deteriorate. Never use a filter that is torn or doesn't completely cover the grill. When dirt can pass the filter it's going to stick to the damp fins behind the filter and restrict air flow. Foam replacement filters are available at hardware stores that can be cut to size with scissors. When cleaning or replacing a filter, be very careful not to move or bend the small tube that runs in front of the coil. This tube is the thermostat sensing bulb and shouldn't touch anything.
When replacing filters, examine the fins on the coil. If you find an accumulation of dust, brush the fins gently with a old soft toothbrush then vacuum the loose dirt off.
The tiny aluminum fins on the coils are very easy to crush. they should not touch each other. Separate any crushed fins using the tip of a knife blade. Some air conditioners have the cone condenser coil fins exposed on the outside of the unit. When these are at ground level, where they can be reached by children, they should be checked often. I saw a unit in an office window that had every inch of the fins crushed. There was no way air could be freely blown through the coils.
Arrange furniture and curtains so that they don't interfere with the free flow of air into or out of the unit. There are clear plastic deflectors available that help to redirect the air flow. The air should be directed in such a way that it is blowing out and up towards the ceiling. When a unit is at ground level, make sure that shrubs, grass or weeds don't cover the vents on the units.
My mother once had an air conditioner repairman condemn her air conditioner saying it wasn't worth fixing; she purchased a new unit. When the old one was being removed from the window, we discovered that the glass storm window had accidentally closed behind the unit. There wasn't anything wrong with the unit at all.
Anytime an air conditioner is not working satisfactorily, before you call for professional service, check everything that could possibly interfere with the flow of air. If the unit is not running at all, make sure the plug is firmly in the outlet. If it's a 110 volt outlet try a lamp in the outlet to make sure the outlet is live. Then check the fuses or circuit breakers.
A simple test can be performed to determine how much a unit is cooling. Tape a small thermometer onto the front grill where the room air enters the unit. Run the unit on the coldest setting at low speed for 10 to 15 minutes and then read the temperature. Next, tape the thermometer to the grill where the cold air is being blown into the room. Wait 10 to 15 minutes and take another reading. If the difference is less than 10 degrees your unit is in need of professional help. Ideally, the difference should be about 20 degrees.
A unit that is undersized for the area that is being cooled will not cool satisfactorily. On the other hand, a unit that is oversized will cool the area so fast that the unit will shut off before the air can be dehumidified. The air will be cold but damp and uncomfortable. For this reason, it's extremely important to buy a unit of the correct size for the area to be cooled. Bigger is not always better.
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