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ChrisDIY 03-12-2011 07:28 PM

What did I do? Heat Pump isn't working

I noticed the other day that my thermostat wasn't doing anything when I select "emergency heat." I have Goodman single stage heat pump, Rinnai hydronic air-handler and Aprilaire 8870 thermostat.

After reading the wiring diagrams for all components, I disconnected the "O" connections from the to the board and from the heat pump to the board on the air-handler and connected the two wires together in a wire nut. Which is how it is illustrated in all three wiring diamgrams. I also noticed that the "B" wires weren't connected so I connected them in a wire nut. When I turned the power back on the fan ran continuously. The heat pump on the outside wouldn't start but I was now able to get the unit to respond with emergency heat (hydronic coil). Reversing my work, I disconnected the "B" wire nut, and also placed the "O" connections back onto the control on the air-handler. I now have the fan working when there is a call for it but I still have no heat pump. The emergency heat still remains.

What is the easiest check? Buy a cheap heat pump thermostat and see if everything starts working again?


heatycooly 03-12-2011 09:05 PM

The o terminal is for the reversing valve switches the flow of refrigerant b is your common when you are calling for great put your ear by thr electric compartment on the great pump if you hear quiet hum the contractor or switch is closed and should be on then I would say you have a bad capacitor on the heat pump if you don't hear a hum then wiring is the problem or threw is no power to the unit I install goodman and thr same tstat

heatycooly 03-12-2011 09:06 PM

The tstat is fine by the way

ChrisDIY 03-12-2011 11:02 PM

All wires are in "original"configuration and fan will not shut off. It had stopped but has since started to continuously run.

Killed power to air-handler, until I can figure out what is going on.

Also the "B" wire from neither the tstat or the HP have ever been connected. :whistling2: I want to say there was blue, blue with pink stripe, yellow, white and red. I have to try and find the HP manual.

heatycooly 03-12-2011 11:41 PM

Check the low voltage fuse on the air handler if its blown the fan will run continuously

ChrisDIY 03-13-2011 02:38 PM

What is the purpose of the "O" terminal on the air-handler? Is it just for convenience? Just wondering since wiring diagram clearly shows no connection at unit?

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ChrisDIY 03-13-2011 05:09 PM

Got home and checked fuse it was good. Went ahead and double checked wires and when assembled heat pump started. Will see if I get heat...

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heatycooly 03-14-2011 06:22 AM

The o terminal us for reversing valve but most of the time idon't connect to air handler I will use an interface board and just connect it to my tstat

heatycooly 03-14-2011 12:06 PM

So is your system working

ChrisDIY 03-14-2011 03:52 PM


Originally Posted by heatycooly (Post 609087)
So is your system working

As of yesterday, yes, but I am puzzled as to why. The only thing different was I connected the "C" on the heat pump to the "C" terminal on the air-handler that wasn't previously connected. The unit has functioned fine without it being connected. I do not know why the fan was running contiuously... I straightened the wires on the "O" terminal on the air-handler, but I can't believe one of the wires wasn't making contact.

For sure I am not going to touch anything! :whistling2:

Thanks very much for your help!!! :thumbup:

heatycooly 03-14-2011 03:55 PM

Well the c is common wire and yes a loose connection could 24 volt systems are sensitive but glad your back up and running

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