Air Conditioning - Window Air Conditioner -- Poor Preformance
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handyman_perry
05-14-07, 02:06 PM
We have a couple of window air conditioners we use maybe a total of 30 days a year when temperatures are not too hot outside or when it is 100+ outside to reduce temperatures in only sleeping rooms. Three years ago I replace a 20+ year old unit with a similarly sized new unit (12000 BTU). No matter what we do, it just does not seem to put out air as cold as the older unit or other units in the house. It can be turned on all day when outside temperatures are 80-85 and never get inside air temperatures below 75.
Even with the mechanical thermostat all the way to coldest, the air seems to be only slightly chilled, regardless of how hot or cold the air in the room or outside is. Even on the hotest days, the compressor runs for a few minutes, then shuts down with maybe only 30% on time at best. On our other units the condensors seem to run almost continuously on the hotest days. Airflow seems okay both through the evap and condensor coils, current drawn when compressor is running is slightly below nameplate, the unit does not freeze up on the evaporator. There is no noticable mold, drainage holes are clean, and on very humid days, some water drips from the weep holes outside. We have had it checked by our furnace repair man, who took the top off and said everything looked okay. We have taken it outside and cleaned the condensor coils twice, (we do this yearly with all our window units). We keep the filters inside clean and also clean off the evaporator when dust sneaks through the filter. We have taken it in to an authorized repair place, which simply cleaned it again sprayed some pine-scent stuff in it and sent it back. I can only think of four things which might cause this behavior:
1. The thermostat is bad or miss-calibrated so "maximum" cooling is something like 85 degrees.
2. There is a problem with the charge.
3. Short cycling is caused by a defective compressor.
4. "New" refrigerants just do not work as good as the older types I was used to in the previous unit or other units in the house.
Any suggestions on what to do or where to check next?
Even with the mechanical thermostat all the way to coldest, the air seems to be only slightly chilled, regardless of how hot or cold the air in the room or outside is. Even on the hotest days, the compressor runs for a few minutes, then shuts down with maybe only 30% on time at best. On our other units the condensors seem to run almost continuously on the hotest days. Airflow seems okay both through the evap and condensor coils, current drawn when compressor is running is slightly below nameplate, the unit does not freeze up on the evaporator. There is no noticable mold, drainage holes are clean, and on very humid days, some water drips from the weep holes outside. We have had it checked by our furnace repair man, who took the top off and said everything looked okay. We have taken it outside and cleaned the condensor coils twice, (we do this yearly with all our window units). We keep the filters inside clean and also clean off the evaporator when dust sneaks through the filter. We have taken it in to an authorized repair place, which simply cleaned it again sprayed some pine-scent stuff in it and sent it back. I can only think of four things which might cause this behavior:
1. The thermostat is bad or miss-calibrated so "maximum" cooling is something like 85 degrees.
2. There is a problem with the charge.
3. Short cycling is caused by a defective compressor.
4. "New" refrigerants just do not work as good as the older types I was used to in the previous unit or other units in the house.
Any suggestions on what to do or where to check next?
EYG2181
05-14-07, 03:28 PM
The fourth thought is probably the correct one. the older units work better than the newer ones on most occasions. you could try messing with the thermostat. and if you cant keep the compressor on, try wiring it so it is constantly on.
handyman_perry
06-08-07, 10:48 PM
Solution to problem:
I removed the thermostat and jumpered around it in the circuit. The compressor came on and stayed on and the room quickly came down to a reasonable temperature, and kept dropping to an uncomfortably cold temperature. For a few days, we regulated the room temperature by turning the entire unit on and off.
I located a similar thermostat and installed it on the unit. Now everything is working better than it ever had before. When set side-by-side, the new thermostate would click ON at about mid range, while the old one didn't click on until it was almost completely turned to the maximum cooling position.
I removed the thermostat and jumpered around it in the circuit. The compressor came on and stayed on and the room quickly came down to a reasonable temperature, and kept dropping to an uncomfortably cold temperature. For a few days, we regulated the room temperature by turning the entire unit on and off.
I located a similar thermostat and installed it on the unit. Now everything is working better than it ever had before. When set side-by-side, the new thermostate would click ON at about mid range, while the old one didn't click on until it was almost completely turned to the maximum cooling position.