Trane Alternative Heat not working with Nest


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Old 01-28-18, 04:13 PM
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Trane Alternative Heat not working with Nest

I installed the Nest last May and though all was working well. However, as we moved into the Winter I found that the alternative heat source was not working correctly. The Nest would show that the alternative heat source was on and the blow would come on but it was blowing cold air. Hooked original stat back up and all was good. This is a Heat Pump that both heats and cools and uses and electric furness as a alternative heat source.

I have attached images with the model numbers of the systems as well as photo's showing the wire setups. The unit wiring is a little difficult to see so here is a breakdown.
YO - Yellow
B - 2 Blue wires
R - 2 Red wires
O - Empty
Yi - Yellow
G - Green
W1 - 2 White and a White Jumper to W2
W2 - Whiter Jumper from W1 and a Blue Jumper to W3
W3 - Blue Jumper from W2

Looking for any help I can get in properly wiring this 3 Generation Nest.
 
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Old 01-28-18, 04:20 PM
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How did you have the nest wired ??

It should be like this.....
red ---------> Rh
green ------> G
yellow -----> Y1
orange ----> O/B
blue --------> C
white -------> WH2/AUX

Program stat for heat pump with back up heat.
 
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Old 01-28-18, 04:27 PM
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It was wired just like the diagram in the attachment. I just used the photo diagram nest provided because I had already taken it back apart.

So........
Y1 - Yellow
G - Green
OB - Orange
Rc - Red
C - Blue
W2/Aux - White

I did notice that in the original state there is a jumper between Rc and Rh.
 
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Old 01-28-18, 04:31 PM
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Nest had show that Red went to Rc not Rh...... would that be the problem?
 
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Old 01-28-18, 04:35 PM
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Yes, it was programed for heat pump with back up heat.
 
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Old 01-28-18, 04:40 PM
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The pro install handbook shows it on Rh but with a single transformer like yours.... it's not supposed to make a difference which one is used. No jumper is required.

You'll have to check at the air handler with a meter for 24vac from W to B (common) when in AUX heat mode.
 
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Old 01-28-18, 04:44 PM
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Any other thoughts? or should I try to just hook it up and us Rh and see if it works. Does everything look correct in the wiring of the Unit itself and how it should be for Nest to work properly?
 
 

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