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 No 24v at Compressor Contactor
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ccrider966

10 Posts

Posted - 06/22/2018 :  11:35:28 AM  Show Profile  Reply with Quote
There is no 24v in the low voltage line at the outside compressor that is needed to connect to the contactor. The A/C is set on the thermostat inside and the blower comes on and runs but the compressor does not since there is no 24v signal at the compressor.
I cannot see where the low voltage line running to the outside compressor is connected to the controls at the furnace. I am still looking for that connection so I can tell if the lack of 24v is due to no signal from the control or if the long low voltage line is broken somewhere.
I have a very lightly used Lennox G20-E unit that is a 1992 model that is in good condition otherwise. This problem just surfaced last week.
Any ideas where I should determine why the missing on the 24v low voltage line?
I measure the BCC thermocouple voltage of R to Y as 5v. Also the R to Ground is 26v and the Y to Ground is 20v taken with the blower running.

Cozy.Support

5989 Posts

Posted - 07/06/2018 :  08:34:08 AM  Show Profile  Reply with Quote
"R" is routed to the thermostat and then the thermostat sends the voltage back to the "Y" terminal upon a call for cooling.



CozyParts.com, Inc. is an Independent Lennox Dealer providing a national parts distribution resource for Lennox parts since 2002. The Cozy.Support team does not provide a diagnosis for users of this forum. We do, however, try to provide information that will help servicers arrive at their own diagnosis.

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