Thermostat Transformer

Apr 30, 2008 8 Replies

My White Rogers programmable thermostat died yesterday. My wife came home and found the house "very cold" so she turned the system off. When I looked at the thermostat I found the LCD panel was backlit but wasn't displaying anything so I swapped it out for the old mercury-switch thermostat, which I had saved.



In the process, I shorted a couple of wires together. I saw a spark and now there is no voltage between the red and blue (common) wires. None of my circuit breakers appear to be tripped but two adjacent breakers are linked and labled A/C so I toggled them anyway, which did not help. Are these two linked breakers likely just for the compressor or for the air handler also?



I traced the thermostat cable up to the attic where they go into a side panel of the air handler cabinet (Goodman ARUF). I presume that the low-voltage transformer is inside, right? Are these transformers typically fused? If so, can you tell me where it is?


Never mind. I found the purple fuse and it's dead.

Bob Simon posted for all of us...

ALL fuses turn purple after they are dead. It's called lividity - like when a person dies. The cause and manner of death needs to be determined. I would bypass CSI and move right to HVAC for this one.

Set your meter to ohms scale and check to see if there's power across the transformer primary winding.

over a barrel posted for all of us...

Burn baby burn ~~~~~ disco inferno burn baby burn ~~~~~~~~~~

Wasnt a fluke I swear.

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