Transformer or T-stat?

Problems related to residential installations.

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Transformer or T-stat?

Post by tdbrown » Tue Jan 04, 2011 8:13 am

Hello All,

I have been playing with my heat pump (Amana ARUF-049) every winter & this year is no different.

I installed a Honeywell programmable T-stat at the beginning of last winter and the system muscled on through the summer heat without an issue.

The primary side of the x-former burnt out this round. I replaced it last night and it went out shortly afterwords.

Here is my thinking, after my all nighter - I incorrectly installed the t-stat, by connecting the "C" Blue wire, when I was directed not to, per the directions... It just didn't make sense last year.

My new direction of pleasure - (1) Disconnect the "C" Blue wire at the T-stat, (2) perform a short test on the wires and (3) replace the transformer again.

Can anyone reflect on or confirm my diagnosis & theory of my corrective actions? I greatly appreciate your time and expertise, from one & all, as I am a true Jack of All Trades, yet Master of None.



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- Transformer or T-stat?

Post by nomadpeo » Sun Jan 16, 2011 1:13 pm

if i read you right, you said you replaced the thermostat at the beginning of the winter and it ran through the following summer. this would indicate that you did not wire in a direct short and that this is a new problem. for that reason, i don't think you should start by changing the wiring.

you do have a direct short in the low voltage somewhere if the primary of the transformer opened. (by the way, does your air handler not have a circuit board with a low voltage 3 amp fuse onboard ?) as suggested, if you place and inline fuse in the red wire going to the thermostat, it will blow if the short presents itself.

the best way to troubleshoot a problem like this is to rule out what is not the problem. i gather you have a digital voltmeter. do you have a clamp ac amp meter ? i find the most effiecient way to identify a solid short is to isolate the loads and connect them one at a time. you can do this without an amp meter by finding out which 24 volt load blows the fuse. let us know if you need any further guidance. good luck.

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