EcoRenovator - View Single Post - Reverse air conditioner freeze up problem

jeff5may · 10-26-14, 08:20 PM

the cheapie thing you want is this:

DT45 Refrigerator Defrost Thermostat L 45 Degree w Clip for for 1 4" 5 16" | eBay

Wire it in series with the compressor, clip it onto the tube running from the evaporator back to the compressor (not the one with the capillary tube). When the coil freezes up, the contacts open and stop the compressor. The contacts close again when the tube has warmed from thawing. You can tweak the operation by moving the thermostat to different points on the copper tubing.

To answer your question about running a frozen evaporator: the compressors in window a/c units are not built the same as those in freezers and refrigerators. They basically are all guts on the inside, with not much breathing space. There is not much room for extra heat, refrigerant, oil, or anything in there. They are also optimized to run at a certain compression ratio and volume flow.

When the evaporator freezes, a few things happen. Heat flow into the evap slows down, causing the boiling of refrigerant to slow. This forces more liquid further through the evap and sometimes into the compressor. Compressors don't like to see liquid at all. During moderate events, things like bent or cracked valves happen. During wet events, burnt windings, bearings, stalled rotors happen. Not good...

10-26-14, 08:20 PM	#6
jeff5may Supreme EcoRenovator Join Date: Jan 2010 Location: elizabethtown, ky, USA Posts: 2,428 Thanks: 431 Thanked 619 Times in 517 Posts	the cheapie thing you want is this: DT45 Refrigerator Defrost Thermostat L 45 Degree w Clip for for 1 4" 5 16" \| eBay Wire it in series with the compressor, clip it onto the tube running from the evaporator back to the compressor (not the one with the capillary tube). When the coil freezes up, the contacts open and stop the compressor. The contacts close again when the tube has warmed from thawing. You can tweak the operation by moving the thermostat to different points on the copper tubing. To answer your question about running a frozen evaporator: the compressors in window a/c units are not built the same as those in freezers and refrigerators. They basically are all guts on the inside, with not much breathing space. There is not much room for extra heat, refrigerant, oil, or anything in there. They are also optimized to run at a certain compression ratio and volume flow. When the evaporator freezes, a few things happen. Heat flow into the evap slows down, causing the boiling of refrigerant to slow. This forces more liquid further through the evap and sometimes into the compressor. Compressors don't like to see liquid at all. During moderate events, things like bent or cracked valves happen. During wet events, burnt windings, bearings, stalled rotors happen. Not good...