2011 HVAC w/gas furnace. When switched from a/c to heat or vice-versa its always a problem. Switched again after a/c was off for about a month and can’t get anything to work; no fan when switched to “on”; no led diag lite coming on furnace board. Cycled breakers and furnace switch, checked for power; receiving power at the switch but not getting anything on the control board.
I’m starting to think it’s a wiring problem, 4 other people in sub-division have the same problem every time they go from a/c to heat. Did I mention the installers were fired halfway through the job?
Unit is a Comfortmaker M9MP205208. Unit was manufactured in Apr 2011.
Call your local utility. Most do furnace work & since they are not commission based, they have no reason to lie to you. The shop that serves your area has probably done work at that sub division before and if it is a common problem there,
they may already have had a lot of experience fixing it.
That and you can usually put any/all repairs on your utility bill.
PS- Do you have “No Heat”? Then tell them that over the phone.
Not insinuating anything, but is the pilot lit? Sometimes, the gas company purges a main line before the winter “load” hits, and it only takes a second or two for the pilot light to go out.
ETA: I thought this when you mentioned the other neighbors having the same problem.
Serious? I’ve never heard of this, and it seems like a really bad idea, and unnecessary, since many people will have gas stoves. What are they purging? You got a cite for this?
RyanHomeSuck, what wiring do you suspect? Can you check the wiring to the thermostat, both at the furnace and at the thermostat? See if the right color wires are attached to the labeled connections. (There are two colors that can be interchanged, yellow and blue, I think. Hopefully and HVAC person will weigh in here.)
Another thought: some thermostats need a fifth wire, to supply power to them. Some thermostats get around this for a four-wire setup by pulsing the furnace or AC on and off quickly. Here’s a blog from someone talking about problems he has with this, using a basic Honeywell thermostat.
I Googled the unit number you gave, but it didn’t give any results. Is that for the thermostat? Maybe post the model for your furnace as well.
I may have found the problem. The transformer does not seam to be working. I have somebody coming out that has one. He also thinks 2 wires are inverted. I’ll let you know what happens. Thanks for the replys!!!
I should clarify that you wouldn’t have both colors of wire. You might have a blue wire attached to the screws labeled “Y”, and no yellow wire.
ETA: or the transformer. Yeah, just about to mention that. Hope that fixes it.
Problems; (1) an extra blue wire demanding an extra 208 volts was hooked to the furnace’s thermostat block (2) making the transformer work twice as hard, burning it out after only 3 years. Solution: remove the extra (208v) blue wire; replace the transformer.
You gotta love cheap a#s builders that construct $300K+ homes using the lowest bidding subs. Good ol’ Ryan Homes.
For all that replied; thank you. I’m taking off my sweater now. Have a good evening. :-)
208 volts? Guessing you’re in Con Ed territory, or at least in the New York area. Certainly a relatively inexpensive area. Around here, the homeowner would need to do most of the work themselves to be able to make a house for $300K.
Good that you got it figured out, and now you can spread the news to your neighbors. Their systems were probably all installed by the same person. Of all the possible things, a mis-wired and blown transformer is one of the cheapest things that could have gone wrong.
Hope that fixes it.