Hmmm...I believe it is just a furnace, I noticed window unit A/Cs. Could be an A/C system but i did not see an ?evaporator? (inside) coil's housing area. I thought a heat pump worked from the compressor, which would be outside. So I think it is not, as there is no outside unit. I did not think to look at the thermostat to see if it had an A/C mode.

quote Originally posted by Taijiguy: If it's got a/c, that's a bit more complicated, but not impossible. If it has a heat pump, you might be better off calling an HVAC guy. (Hey, dohc_swapper, see what I did there??)

Man there are a lot of wires in that panel. More than the other switches lonely saint's fan's contribution would support. Good thing is most are hooked up and I recognize the switches he is talking about and can trace those wires.

OK, these are the most common wiring terminations. Be careful when messing with the wiring as there will be both 24 volt, and 120 volt wiring in the same enclosure. The 120 will naturally be heaveir gauge, isolate 120 power, and then check those connections first. Then start in on the 120. Based on what you've said, the first place I'd look is the power from the transformer, and then the white or blue wires, one of which will supply power to the control valve. The good news here is that your problem is a lack of power to the control valve, which leaves it somewhere in that (relatively) simple circuit. YOu shouldn't have to screw around with the fan limit switches or anyting like that.
Here's a typical wiring legend. The letter designator indicates the termination on the thermostat, you can trace the wires entering the furnace from the thermostat and get an idea of where it should be going:

• (R), Red, hot side of transformer.
• (C) Common side of transformer (See B)
• (W), White, Heat.
• (G), Green, furnace blower fan.
• (B), Blue or Orange, Energize to heat (used on some systems).
• (B) or (X), Blue, brown or Black, common side of transformer. Needed on some electronic thermostats or if you have indicator lamps.

Ok, the wiring will work something like this on most gas furnaces:

You'll have 110V come into the furnace and to go a transformer. That knocks the voltage down to 24v. 24v goes out to the thermostat, and then back from the thermostat to the furnace. When it gets to the furnace, it runs through a "limit" switch (a temp switch to cut the furnace off if it overheats) and then to the gas valve and back to ground (on the other terminal on the transformer).

You'll have 110v run to the "fan" switch and then to the blower motor, and then to ground.

It sounds like the 2 blue wires are part of the same circuit, and you need to trace it out where the bundle of wires comes back from the thermostat to the furnace and to the gas valve. Check with a voltmeter hooked to the ground on the 24v side of the transformer. You should read 24v going to the t-stat, and 24v on the blue wire back from the t-stat. Then trace the wire and make sure 24v is getting to the gas valve.

Typically, red is the color for the 24v hot wire from the transformer to the thermostat, and white or blue (blue in your case) is the line from the thermostat back to the gas valve.

One thing you have to be careful of is if you short out the gas valve, even with just 24v, you'll burn out the thermostat and it will have to be replaced.

Here are a few info sources:
http://freepoolheat.com/bogden/
http://www.hvacmechanic.com/tstatwiring.htm (thermostat wiring color chart)

quote Originally posted by Formula88: It sounds like the 2 blue wires are part of the same circuit, and you need to trace it out where the bundle of wires comes back from the thermostat to the furnace and to the gas valve. Check with a voltmeter hooked to the ground on the 24v side of the transformer. You should read 24v going to the t-stat, and 24v on the blue wire back from the t-stat. Then trace the wire and make sure 24v is getting to the gas valve. <snip>

This might only occur if the door to the furnace is in place. Some furnaces have an override that stops 120 if the cover is off. If you see some sort of switch that is actuated by putting the cover in place, override it by taping it down. Also, the thermostat needs to be turned up, and the switch set to "HEAT" (if applicable) It's best when testing to just turn the thermostat all the way up, as, if it thinks its satisfied, none of your tests will be accurate.

[This message has been edited by Taijiguy (edited 12-07-2005).]

Thanks.

quote Originally posted by Uaana: Or throw on an extra blanket.. darn southern ninnys. Give us a call when your high for the day will be 5f.

I have to go out of town for awhile and she is on the way. I'll give it another shot and bring her a blanket just in case.