Is my A/C compressor shot?

[Dave Cole]

Have an armstrong A/C on top of my '69 Tradewind. both the inside and outside fans seem to work fine (they are on whenever the A/C breaker is on--seemingly regardless of thermostat setting) but there is not a peep from the compressor. I got up on top of the rig and took the covers off--other than some old mud-dauber nests, there didnt seem to be anthing wrong in terms of wireing.

does anyone have any suggestions before I rip out the old compressor and start looking for a new one?

dave

[davidz71]

Dave,
You have a small transformer on the roadside of the AC after you take the shroud off. This transformer steps 125 volts (my current measurement) down to 24 volts and sends the current down to the thermostat on the wall. The compressor is intended to operate on 115 volts, 60 cycle current and if voltage is under 103 volts, the compressor may not start. Make sure the themostat is set below room temp. Turn the rotary switch of the AC on. The comp. relay should be energized. If not, short between Y and R terminals (noted on your wall thermostat after removing the cover) with a short piece of jumper wire. This is a low voltage circuit. If the comp. relay closes, thermostat is defective or circuit to transformer is faulty. I found no current at my thermostat and less than 9 volts of current on the stepdown side of my transformer. I went to an electrical supply house (taking the old transformer with me) and found one to match which was only slightly larger in exterior dimensions than the original. I made a new mounting bracket, wired it in and the compressor fired up as soon as I turned the AC on. Be careful if you are not connected to a 30 amp circuit. An extension cord to a 15 amp circuit and dogleg adapter to 30 amp male plug can be used to check the unit but should not be run for more time than to see if the fan is running and the compressor kicks on. You may be lucky and find it is only the transformer. Also check that all wires are tight at the thermostat. Let us know what you find.

[winner]

When I had my 1984 270 MH, the compressor went out and I was faced with your same problem., Somehow I was able to obtain the address of an individual in California that rebuilts A/S compressors for between $100 snf $150. As you know, A/S gets about $700 for them. You might consider that