One of the most frustrating problems
with a window air conditioner is if it starts to ice up. For the owner
of the air conditioner is can be perplexing.
this problem occurs most people immediately think it is the fault of the
refrigerant gas. More often the cause is the result of other
It is most often the result of poor airflow. Any time the airflow through an air
conditioner is restricted the cooling system becomes affected. If taken
to extremes the critical pressure-temperature balance of the cooling
coil can be changed. When this happens the cooling coil will begin to
operate as a refrigerator rather than an air conditioner. Rather than
simply cooling the air it will collect and hold moisture, freezing
onto the cooling coil where it will appear as ice.
It must be understood that the
primary job of an air conditioner is to de-humidify, not refrigerate,
the room air. Removing moisture from the room air gives us a feeling of
comfort. This is at the central principle in the operation of the air conditioner. To do this though the temperature of
the cooling coil must always be higher than the room’s dew point. If
allowed to drop too low the cooling coil will begin to refrigerate and produce the icing-up affect so many people encounter.
With this aforementioned airflow
problem in mind the following are a few problems that can result in your
air conditioner icing up:
1... Dirty filter.
2... Dirty or blocked cooling
To avoid this problem replace or clean your filter every couple of weeks
of the cooling season. If a smoker do it every week. To clean filter
remove from air conditioner, wet thoroughly, and lay in bottom of a
sink. Sprinkle detergent (laundry detergent works well) onto filter
surface. Allow to sit for a few minutes. Next, add warm water to sink
until filter is completely covered. Soak for 15 minutes. Remove from
water and rinse. Allow to
An air conditioner requires regular maintenance. Every two or three
years is typical. Every year would be best, but can be costly unless
you do it yourself. During cleaning the cooling coil should be
degreased and washed to remove accumulated dirt and debris.
Degreasing is important to remove any coatings on the coil that
might trap or hold air borne particles. Dirt particles on the coil
will lower heat transfer. Eventually excess dirt results in the
cooling coil becoming partially blocked which reduces airflow.
3... Dirty or blocked condenser
The condenser coil is the one at the rear of the air conditioner.
Its job is to dissipate the heat that is being removed from the
room. Just like the cooling coil it too must be cleaned regularly.
Since the condenser is on the outside of the home it becomes exposed
to a lot of dirt, pollen, and smog. To clean it the air conditioner
must be completely disassembled. If not cleaned an airflow blockage
here can even burn out the compressor. Before this happens though
the lowering of airflow will affect the overall operation. This can
result in the compressor efficiency dropping, the internal
pressure-temperature relationships being affected, and the resultant
production of ice on the cooling coil.
4... Inefficient compressor.
As describe above an inefficient compressor can cause icing up. If
it is unable to pump the refrigerant properly the cooing coil may
not get cold enough to shut off the cold control. It can hover just
above the cut off point. When this happens the cooling coil will
begin to refrigerate. Ice on the cooling coil will result. If the
compressor is at fault the cost of replacing it is prohibitive. But
note that many icing problems are misdiagnosed as bad compressors
when they were actually one of the other faults discussed in this
5... Not enough refrigerant. Too
Both scenarios can result in an icing condition. If your air
conditioner was repaired recently suspect too much refrigerant.
Mixed with an airflow problem this can be difficult to diagnose. If
not repaired recently then suspect airflow problems before
considering a refrigerant imbalance.
6... Outdoor temperature too low.
Icing can occur if the outdoor temperature falls below 60 Degrees
Fahrenheit. If the outdoor temperature is too low the air
conditioner pressure-temperatures can be affected. When the outside
temperature falls so will the the cooling coil temperature. So much
that the coil will refrigerate the room air resulting in the cooling
coil producing ice. This problem is prevalent in the fall.
Therefore, if it's a hot day followed by a cold night suspect this
as the cause of icing. To alleviate the problem run the air
conditioner in the 'fan only' position at night while leaving the
re-circulating vent open. This will circulate the room air without
cooling it, while bringing in a small amount of cool outdoor air
during the night.
7... Oversized air conditioner.
If the air conditioner is too large for the room size icing up can
result. If oversized the air conditioner can short-cycle. This
condition results in the air conditioner starting and stopping every
few minutes. Even though it runs almost constantly the air
conditioner will give poor cooling. Use a sizing chart to determine
what is the proper air conditioner size for that particular room.
8... Cold control not shutting
If the cold control does not shut off the cooling coil surface
temperature will drop below the room’s dew point and begin to
refrigerate. This will allow ice to build up onto the cooling coil.
Cold control bulb broken or loose.
As in the previous paragraph this will result in the cold control not
shutting off and ice to build up on the cooling coil. If this is
suspected remove the front grille and inspect the bulb. If broken
replace cold control. If bent, kinked, or not securely fastened suspect
a problem here.
Copyright © 2006 Donald
Grummett. All rights reserved