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I have a Honeywell Programmable Thermostat T8600 and nothing displays. It was working fine, and the A/C was on on Saturday. I checked the display on Sunday and the thermostat was blank. All other lights are on around it so the circuit braker is fine, and the a/c was working the day before. I have taken the front part off the wall and the wiring looks fine, but I am not an electric expert. I don't know if there is something simple I can try to fix it. Thanks.

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Check your transformer for power, should get 24V reading, if transformer is out make sure there are no short otherwise your new one will have the same fate.before checking the transformer however, make sure that your dedicated breaker for the air handler and your switch in the attic is turned on.

Posted on Apr 10, 2010

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