Dan O. -- Wednesday, 31 July 2002, at 1:14 p.m.
: Okay, what would be forcing the cold air back
: into the unit?
Curtains, a cabinet or other furniture in the way, running the unit without the front grill installed.
: The icing on the coils, thick
: and white, is still there.
"Ice" is usually clear, "frost" is a white snow-like substance. The distinction is important.
: We've tried
: everything we can think of: tilted the unit
: for better drainage;
That will not effect operation of the unit, only moisture drainage.
: unplugged everything
: from the receptacle so the unit is the only
: thing plugged in;
That's a good idea but as long as the compressor is running, it will not effect operation of the unit.
: turned the air sweeper on
: to move the air around instead of just
: forward; turned the fan on high and the temp
: to 7 instead of 8/9; turned the temp to 9.
: The fan is running and air is coming from
: the vents but the ice is blocking the air
: from entering the coils. This unit is only a
: few years old and run in the summer months.
: It shouldn't be low on coolant, should it?
No, if it were short of refrigerant, only part of the evaporator coil would frost.
If it is frosting totally, either the air temperature (inside or outside) is too cold or it is an air flow problem. Maybe the motor is not turning fast enough, the fan is slipping on the motor's shaft, the filter is completely plugged or one of the air flow problems mentioned above.
I have heard that on a perfectly functioning window air conditioner that was frosting completely even in high ambient temperatures, it was speculated that the condensation which was forming on the evaporator coil (which is normal) was causing an air flow problem itself. Some newer more energy efficient models have a very dense evaporator coil which could possibly get restricted by moisture on very humid days. Turning the A/C thermostat down might help the unit to cycle a bit more often to allow the excess moisture to drain away before causing such an air restriction.