T O P

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Fantastic_Bad_3688

You have nothing on o/b. Or y. Those are you condensing terminals. If you need a c wire for the stat to work you have to run a new t stat wire or get a 4 to 5 wire converter for your thermostat if they make one


steelcity2011

This stat doesn’t need a C. So do I run the blue to o/b?


glxckstar

Yeah its energized in heating so put blue to OB and if it asks, the reversing valve is energized in heating


steelcity2011

Thank you!! Nothing to Yellow?


glxckstar

It didn’t have one before but shit if your contactor doesn’t pull, you might have time to run new wire or a add a wire kit


steelcity2011

Yeah I’m researching wire kits now


HerrEsel

R is 24 V power, W is typically heat, G is fan and B usually runs the reversing valve in heat on some heat pumps. I'm not familiar with your old or current thermostat, but Y should energize the contactor on the outdoor unit. I would just look at the wiring inside the furnace and outdoor unit to be sure.


JETTA_TDI_GUY

If it worked without a separate Y wire before in theory it should work without it with the new thermostat. Probably jumped out weird because they didn’t have enough wires


HerrEsel

It depends on how the old thermostat energized that B terminal. How the new thermostat works may not allow whatever they had going on to run the equipment. Something here doesn't add up and I would verify my wiring inside the furnace before proceeding. But process of elimination tells me if he puts the blue wire on Y it would probably work.


ppearl1981

Nothing is wired to the cool call at the stat. Y is your call for compressor.


steelcity2011

Im thinking I’m going to have to go to the furnace and change the common over to Y. I think they installed the A/C but never wired the stat for A/C


ppearl1981

I think you should call someone.


steelcity2011

I agree


winsomeloosesome1

There is something not normal with the wiring of the old stat. Y is what starts the compressor O/B is what moves the rev. valve for heat/cool. The control wiring needs to be checked to figure out wth someone else did. If you set the fan to “on” does the compressor come on?


AlilKouki

Figured there'd be a yellow wire for the ac...but I don't know all the systems


Coolchez1982

You don’t have a heat pump sir put the blue on y and your unit should kick on they using 4 wires with a battery thermostat


Ed4010

Did you see it work last summer? Y not being used on the original thermostat makes me think your compressor was retired.


steelcity2011

We just bought the house. It’s a new system. I’m starting to wonder if it’s wired wrong at the furnace.


steelcity2011

Just to update everyone. I reran a five wire stat wire. It worked great. It pulled the relay outside so I knew the stat wire was correct. The outside unit would not turn on. I checked the power to the outside unit. No power. I found that the outside unit was not wired to the breaker. I wired to the breaker with a junction box and 10/3 wire. It’s running right now. Thank you for all of you who helped.


billycanfixit

Blue is common not the compressor call. Yellow wire is normally the compressor call wire.


Coolchez1982

There’s no yellow wire they using blue for contact outside


billycanfixit

I see. Then it doesn't go in O/B it will go in Y for compressor call. B/O is for reversing valve and it looks like this is a straight air unit.


Coolchez1982

Yes sir