I had a minor accident with my old thermostat so I'm having to replace it, I ran into a small problem though while tracing my wires back. On my thermostat, I have Rc/Rh which are jumpered together, and a W Y G. I understand all of that and how the thermostat works, but my problem comes at the other end, on the unit. It's a Heil NUGE100BG01.

I have W Y R G C on my unit, everything was working fine before, but the Y wasn't plugged up. That really threw me off because I assumed that Y on the unit would be AC compressor too.

Thanks in advance,
Chris Webb
Electrician

There should be a two wire from the furnace to the outdoor unit, one wire should be connected to the "C" terminal and the other should be tied to the yellow wire. Doesn't have to be on the circuit board.

Quote:

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Originally Posted by hvacservicetech_07

the other should be tied to the yellow wire. Doesnt have to be on the circut board.

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The yellow is on the G terminal at the unit. Should it be on the Y at the Thermostat?

What color wire was on the G terminal at the thermostat? They should match unless they have been spliced elsewhere.

It's yellow now.

I knocked the old thermostat completely off with a dresser I was moving, the wires were totally off the old one.

Ok, what color and how many wires do you have at the thermostat?

This is what it should look like...

R-24volt RED WIRE
W-HEAT... White wire
G-Blower... Green wire
Y-Yellow wire... A/C

W= red wire
Y= no wire
R = green wire
G= yellow wire
C = black wire


Those wires are in a cable assembly and run straight from the unit to the Thermostat, no splices.

Do you have air conditioning installed on this system?

Yes, there is air conditioning, and it has always worked. The Y on the unit must have never been hooked up.

Should it be hooked up, what should I do

If I go from G on the unit to G on the Thermostat, and W To W.

Does that mean I hook C to Rc/RH?

What do I do with the wire hooked to the R on the unit?

The wire that is hooked to the C' terminal, is it from a separate cable at the furnace?

R on the unit goes to Rh/RC on the stat with a jumper. W goes to W, G goes to G, regardless what color

There's a labeled terminal board that has 5 connectors at the unit, those are labeled as W Y R G C and there are a couple of wired staked onto the back that lead into a box. I can only assume there are relays in there.

The C is in the same bundle of wires that runs to the Thermostat. I traced it all out. It's just a little bigger that phone cable, but in a bundle the same way. I didn't see any splices on it. Just straight into the basement, across the floor joists, over to the hole where it terminates.

Can I start crossing wires to see what comes on. Using the common? I would hate to have to do that, but if it won't damage my equipment, I would do it.

If you short 24 volts to the common you will have problems, possibly short out the transformer

It sounds like you have a wiring mess. Chances are they have a splice somewhere. Can you post a picture of the furnace circuit board and wiring connections? That may help me a little. If it's a straight shot from the furnace to the thermostat you can hook the thermostat as I posted earlier.

I crossed wires, apparently the C was RC/RH. That was the green wire. Red was W, The one that was on R was apparently controlling the compressor somehow... It doesn't make any sense to me, and I KNOW it's not right, I'm just tired of messing with it.

How many wires are sticking out of the wall, and what color?