A/C Compressor not activating

[gtrump]

I have a 2013 TB27 Pioneer with single AC, wall mount Thermostat. 2 weeks ago, the AC worked; yesterday went to get unit ready for weekend trip and the AC was not working. The fan turns on and off with thermostat set on AC , but it appears the compressor is not activating. I was hoping to be able to troubleshoot the issue and repair myself....any ideas?

 

[danemayer]

Hi gtrump,

If your air conditioner has a return air grill in the ceiling, shared with a cold air dump grill, above that you probably have a gray metal box with relays. The thermostat probably connects to that box and likely fires the air conditioner blower and compressor. But if the blower is running, the problem could also be on the roof. If you remove the shroud on the roof, be prepared in case insects have nested inside. You don't want to fall off the roof.

 

[gtrump]

The blower does run, but it appears the compressor does not (there is no real power flux or clicking when the AC should be coming on).

What am I looking for when I find the relays or when I remove the shroud?

Is there a way to test that the thermostat is sending the AC a signal to turn on?

Hi gtrump,

If your air conditioner has a return air grill in the ceiling, shared with a cold air dump grill, above that you probably have a gray metal box with relays. The thermostat probably connects to that box and likely fires the air conditioner blower and compressor. But if the blower is running, the problem could also be on the roof. If you remove the shroud on the roof, be prepared in case insects have nested inside. You don't want to fall off the roof.

 

[danemayer]

If the fan is set to AUTO on the thermostat and the thermostat is set to COOL, and the set point is below the ambient temp, then if the fan comes on, the thermostat is working.

I'm afraid I don't know much about the contents of the relay box or what's under the shroud. Maybe someone else knows.