Need AC Help ... Very cold and no $$$

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  #1  
Old 11-30-03, 08:15 AM
mark111
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Need AC Help ... Very cold and no $$$

OK, My digital thermostat just went dead last night for no reason. The breaker is on and to the best of my knowlegde power is at the AC unit. Because the thermostat is not working the AC never turns on. Is there a voltage reference I can check for or a bybass to prove the thermostat is the problem. I will start troubleshooting. ANy help is appreciated.

OK, I have 240VAC going to the main relay. What I don't have is 240VAC coming out. The relay has a little contact that can be manually pushed in and ofcourse the AC kicks on. What I can't figure out is why the relay won't stay picked and where the signal comes from exactly telling the relay to pick at the coil.

There must be an AC man somewhere?

Oh.....I'm fairly good at electrical troubleshooting but just need alitlle direction. Thanks
 
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Old 11-30-03, 09:24 AM
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The contactor needs 24vac to operate. The voltage comes from a transformer which is usually found in the indoor unit. The voltage may run through a safety control or two before pulling in the contactor so follow it before you assume anything. The thermostat is usually one of the first things off of the transformer. Start by finding the transformer and and checking for 24vac at the secondary terminals. Be careful because 240 vac won't be far from the area you will be working in. Rule of thumb is don't blame the thermostat until all else has been checked.

Ken
 
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Old 11-30-03, 12:56 PM
mark111
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Fixed. Found a broken wire from the main breaker going to what looked like a thermo fuse maybe. The wire was commoned up with another wire going to the board that controled the transformer. Re-made the wire and everything works as designed. Thanks for the direction.

Mark
 
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