Dan O. -- Saturday, 25 August 2001, at 5:24 p.m.
: My window unit froze up. Anything I can do to
: control this before it happens again?
: Running fine all summer-what causes this.
Being too cold is the most common cause of the evaporator (cooling) coil is frosting over completely. That includes both inside AND outside air temperature dropping below 70°F. Depending on the area you live it, it was colder than that here last night.
: Anything I can do to
: control this before it happens again?
If the cause is temperatures too cold, setting the thermostat to a warmer setting will help the compressor cycle on and off periodically to melt any frost that might form.
Poor air flow can also cause an air conditioner's evaporator (cooling) to frost completely. Make sure the filter is clean, that there are no curtains or other obstacles in front of the unit and that the grill is in place and the air vents adjusted properly.
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.
Dan O.
