Hope you guys can help me out on this one. Friend at work had problem last fall, couldn’t get her furnace to put out any heat (she had moved in in the summer, when the A/C was on). Repair guy came in, said, “oh your RA and RF are mixed up.” Switched them around, left. Furnace heat came on.
Guess what. Hot weather coming, she tried to get AC on to-day. No go. But the heat works fine. She can’t remember which two wires he switched, and honestly, can’t afford to keep calling in a service guy just to switch two wires around.
So we want to know if this is something that she, or she & me, could repair. It’s a White Rogers thermostat (model 9734E143), not digital, There are four wires, white, yellow, mauve, blue. She thinks that one contact is labelled “1” and the other “0” but can’t see markings for the other two.
How difficult is it to buy a digital thermostat and hook that up? Seems to me if we took our time and some effort, we should be able to do it. Appreciate all your help.
Replies
My buddy is an HVAC guy, and I've helped him do many installs of furnaces and A/C's. Every time I did the thermostat for him, he said "blue wire is A/C and it goes on Y post". Most (all?) that I've installed also have a red jumper wire going from RH to RC to give power to both heating and cooling controls...is yours missing this jumper?
Hi
Thanks for the replies. I am the unlucky lady who is hot and wants her AC back up and running. I have posted a pic online of my themostat. My ex-husband recently remembers the HVAC guy telling him to just switch the "two" wires but he conveniently forgets which ones.....anyways.....I have misplaced my receipt with the company info to call the service guy back. Anyone able to help me out? I am sure I can do this for a lot less than 5 minutes and $150.00 (with online help that is).
Any help would be appreciated.
Sorry about that...here is the pic.
You need to remove the thermostate and look at the wiring to the sub-base that it under it.
Here's the link for White-Rogers stuff http://www.white-rodgers.com/homeowner/index.htm
That's probably not a model number, more likely a part number.
Emerson will respond to questions by mail.
Recommend you go the distance for a full digital with 7 day programable (don't bother to try and save a couple of bucks for a 5/2 version, get the one where every day is separately programable). White-Rogers is good, LUX is better: buy one from HD (you are in Canada - right ?) and save.
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Phill Giles
The Unionville Woodwright
Unionville, Ontario
Well, if you're really hot, I suspect there are several guys here who'll volunteer to fix it personally. Just be sure to tell them when your husband won't be home. (;-))
Forget about the picture of the thermostat, I thought she was going to post a picture of herself.
Sorry Marta.
Geez, this is the last time that I lend my name to anyone... The reason my co-worker was thinking about a digital was to have the programmable feature, have the air come on 15 minutes before she got home,,... Must be confusing with two of us posting under the same name. Believe me, the real martagon isn't hot.
Did you get a chance to look at the other end of the thermostat wires, in the furnace? The markings on the terminals there may answer your question.
LUKA!
Get back home. She didn't mean it that way.
Men Men Men..... I tell ya.
There are 4 wires for a standard HVAC thermostat --
-- AC power (about 24v)
-- Heat
-- Cool
-- Fan
In "heat" mode the fan wire is unused unless you switch to "fan on" mode on the 'stat -- there is a thermal switch in the furnace that turns on the fan when the heat exchanger is warm. In "cool" mode the fan wire is connected to the same thermostat contact as the cool wire, so both fan and cooling come on together.
Sometimes the wires get gerflugled at the other end or in a splice somewhere. If you disconnect them and try connecting various pairs together, though, you can work it out. (Eg, shorting the AC wire to the cool wire will cause the outside compressor unit to come on, even though the fan inside doesn't.)
It's not difficult at all to hook up a digital thermostat. They generally come with fairly complete instructions. You will need to sort out which wire is which first, though.
The easiest way to straighten it out is to look at the other end of the wires, at the furnace. Match the wires according to the letters. The wire on screw G at the furnace goes to screw G in the thermostat, Y to Y, and so forth.
If the letters don't exactly match, download the instructions for the thermostat from the internet.
By "digital" I presume you mean a programmable thermostat. They are not difficult to hook up. But you have to take the wires off the old thermostat and put them on the new thermostat according to the same labeling scheme. So, first you have to get the old thermostat to work so you know you have the wires straightened out.
Beware of programmable thermostats that require batteries. Many of them quit when the battery dies. If it dies while you are away for Christmas you'll lose your heat and freeze your pipes. Many also lose their program when you change the battery, so you have to reprogram them every time you change the battery. The Carriers don't have either problem, but require a fifth wire to hook up. If you can easily fish new cable then you can successfully install one.
Home Depot sells digital thermostats for most types of systems. Make sure you get the right one. That is the hard part. I bought a Honeywell unit and hooked it up to control my multistage heat pump. The diagrams furnished did not cover my manufacturer's system, so I logged onto Honeywell's web site and eventually sent them an e-mail describing my HVAC system and the thermostat I had purchased. They got back to me the next morning with the correct hookup information. The system works great.
Why buy a new thermostat?
Pop this section off, and take a pick of the sub base, that's where the important wires are......post it here, and then you'll get feedback.