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Air Conditioning/ Heater/ Blower Nothing Cycling up With Thermostat Controls

Air Conditioning/ Heater/ Blower Nothing Cycling up With Thermostat Controls


  #1  
Old 06-05-14, 03:07 PM
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Air Conditioning/ Heater/ Blower Nothing Cycling up With Thermostat Controls

He guys, I have an old unit that is refusing to submit to my authority. Will not respond to commands through the thermostat. I can put it on cool and turn it down below current temp and nothing, I can turn to heat and turn up until past current temp and nothing and turning to blower only does not get a response.

There is power to the compressor outside and if I manually close the points the compressor comes on. But the blower does not cycle on with any command. I have checked the breakers and all are working properly.

I do not see any broken wires, the thermostat is free of dust and particles. It is only about ten years old. The item appears to ffuunction mechanically corret. Tipping the glass bulb causes the metaal internal unit to be attracted to one side or the other.

The thermostat is an old GE model cht18-60 3aat76a21a55 30vac 1.5 amps. Not sure what the upstairs unit or compressor model/make is, but can access any info that might help explain this phenomenon

My wife is glaring at me.... Thanks!
 
  #2  
Old 06-05-14, 03:18 PM
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The 2 most common causes for this are a tripped float switch at the indoor unit because the drain has backed up and a pan is full
http://i151.photobucket.com/albums/s...n204/PTrap.jpg

or you have a popped low voltage fuse in the indoor unit because the low voltage wire outside is shorted.

http://i151.photobucket.com/albums/s...4/condwire.jpg

http://i151.photobucket.com/albums/s...n204/short.jpg
 
  #3  
Old 06-05-14, 03:20 PM
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Sounds like you are not getting 24 volts,check at the furnace and see if there is a transformer there,with a volt meter check across the terminals for 24 volts,some transformers have a built in circuit breaker that can be pushed in to reset.
 
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Old 06-06-14, 02:19 PM
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Thanks, will check the voltage and then check all of the wires
 
  #5  
Old 06-07-14, 11:30 AM
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After checking the transformer voltage and finding it correct, I ran the wiring until I found a break in it. Mice had decided to chew through the wires at a point where it went under the flex pipe. I repaired the wiring and the unit came on and functioned correctly.

However, I had to turn the power off to reattach the attic units external cover and when I attempted to turn the power back on the blower motor growled, but did not spin up the blower fan. The fan can spin freely, so no obstructions or failed bearings. Is this a function of the starter capacitor? And the fan motor became too hot to touch from the small amount it ran while I was testing it. Thank you for the assistance guys!
 
  #6  
Old 06-07-14, 11:48 AM
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It is unlikely that your indoor fan motor uses a start capacitor. They usually use a run capacitor.

It could very well be a capacitor problem.
I would verify that one of the wires to run cap hasn't been unplugged.

I like my meters and probably have a dozen that can measure capacitance but most posters just replace the cap rather than getting a meter because caps are so cheap.
 
 

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