Honeywell RTH8500 Wiring help


  #1  
Old 07-03-14, 08:22 AM
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Honeywell RTH8500 Wiring help

I just replaced a Robertshaw thrmostat (don't know the model) with a new Honeywell RTH8500. I did the installation myself, but am now having trouble with the AC not coming on (heater is working fine). The Robertsmith came with our new built home, but had to be replaced because the fan would not shut off.

In my old thermostat came with the following wiring setup:
Green wire -> G terminal
White wire -> W terminal
Black wire -> B terminal
Red wire -> RH terminal (jumper connected to RC)


Here's a link to the old thermostat configuration
https://imageshack.com/i/mv52etj

Name:  stat.JPG
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Now on the new Honeywell RTH8500, there are the following terminals:
Rc, R, W, Y, G, C
There is a jumper wire connecting Rc to R.
I connected the existing wires as follows:
Red wire -> R terminal
White wire -> W terminal
Black wire -> Y terminal
Green wire -> G terminal

Like I said, the heater still works fine, but AC does not come on at all. The fan works

Did I messed something up? This is a brand new house and silly us, we didn't check the AC during the PDI.

Any help would be appreciated.
 

Last edited by PJmax; 07-03-14 at 11:33 AM. Reason: added picture
  #2  
Old 07-03-14, 08:30 AM
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I can't get to the image, but I will give it a shot. On the old stat you don't list Y, is thre a yellow wirecoming out of the wall? The black wire needs to land on C in new stat.
 
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Old 07-03-14, 09:45 AM
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No yellow wire, which i was actually surprised.. already tried placing the black wire to the C terminal.

thanks for replying.
 
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Old 07-03-14, 11:00 AM
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I have never seen a thermostat cable with a black wire in it.
 
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Old 07-03-14, 11:38 AM
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I inserted pic for you.

W1 will be Y
I think Black - B is powered for heating (reverse valve) if this is a heatpump
Red - Rh/Rc
Green - G

If this isn't correct then you'll need to check and see where the wires are connected at the air handler unit.
 
  #6  
Old 07-03-14, 05:49 PM
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Tried that configuration and it just blew hot air when I tried the cool function and nothing happens when I tried the heat. I'm starting to believe that the wiring isn't the problem. The fan for our AC unit isn't spinning.

Thank you for the suggestion. I'll be open to any other ideas and suggestions.
 
  #7  
Old 07-04-14, 04:38 AM
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Do you have a heatpump? You have to go into the settings menu and make sure the settings are correct for your system.

They ship from the factory set up for single stage forced air heat /w a/c. If you have anything different, you have to change the settings.
 
  #8  
Old 07-04-14, 09:35 AM
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with the muggy weather that we are having, i had decided to call someone to have it looked at. as it turns out, i was right; the wiring was correct. the issue was a blown fuse, which is again something that is new to me (you got to start somewhere)

anyway, thank you to those who had responded.
 
 

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