Installing thermostat: A/C Won't turn on


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Old 09-25-11, 12:46 PM
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Installing thermostat: A/C Won't turn on

I installed a new thermostat and the unit won't turn on.

I then re-installed the old thermostat, which is not-battery operated, and the display wont even light up.

I've reset the breaker and the pull power switch by the compressor.

Any ideas of what the problem could be?
 
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Old 09-25-11, 01:43 PM
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You have popped the low voltage fuse or low voltage breaker in the indoor unit.

If this is an older Rheem/Ruud or Trane/Am Standard gas furnace a fuse may not be present and a new 40va 24vac transformer is now required.
 
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Old 09-25-11, 01:50 PM
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Most gas furnaces use a blade type 3 amp automotive fuse. Most fancoils (air handlers) use a 5 amp fuse. Radioshack has 24vac transformers if you need one but the fuse is the first thing that I would check.

Some examples...







Older Trane air handlers (electric heat) may have this fuse...


 
 

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