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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Trane thermostat is blank. Took of cover and no batteries.

Customer Question

Trane thermostat is blank. Took of cover and no batteries. No circuit breaker flipped
JA: Just to clarify, do you think this is a larger HVAC problem, or something specific to the thermostat?
Customer: Thermostat. Had system checked out last week
JA: Do you plan on doing the work yourself?
Customer: Yes
JA: Anything else we should know to help you best?
Customer: Not they I know of That
Submitted: 2 months ago.
Category: HVAC
Expert:  Phil replied 2 months ago.

Hello, it is likely that the 24 volt transformer in the furnace or air handler that supplies power to the thermostat is failed or has blown a fuse in that circuit.

Tell me if you have or want to get a multi meter to check that voltage, if you do check the red wire on the thermostat terminal strip inside the blower service compartment to ground (any bare sheet metal on the furnace will work for that)

we can go from there

Customer: replied 2 months ago.
What about over fill panic stairs being full?
Customer: replied 2 months ago.
Expert:  Phil replied 2 months ago.

Hello again, there are a number of devices in the system that can shut off power to the thermostat, one of them that you mention is the drain pan float (optional) that can be stuck and killing power to the thermostat.

Another is the door switch on the blower service access panel can not be making good contact.

I could go on,

However what works best is a systematic approach to detecting the 24volt control voltage, that requires a multi meter, then in short order we can discover what the problem is.

Expert:  Phil replied 2 months ago.

First step is determining if you have 24v power to the red wire on the thermostat or not, if you have power there, then the problem is with the thermostat. If you do not have power there, then we need to trace the break in the circuit.

Trial and error works, but can take hours or days. Diagnosis can be done in seconds if you want to follow my lead.

tell me which way you want to go on this. and a lot about your technical skill sets so that I can decide which approach will be most effective in your case

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