Well, I think it’s the thermostat (in my house).
When certain parts of my house get warm, instead of turning on the AC, I usually just flip on the fan and that’ll even everything out over the next few hours (in fact it usually cools the place down becuase it brings some of the cold basement air upstairs). But recently I noticed a problem. When I turn the switch to FAN ON, my AC compressor kicks on and stays on. So last night my house was 77 degrees, I flipped the switch and woke up with it being 66 degrees in the main part of the house, and I’m guessing quite a bit colder in the bedroom. At least it felt quite a bit colder. Now, we just moved into this house last summer and I really don’t know if it was always like this or not. Also, it makes no difference (in my limited tests) what the temprature is set to or wheather the other switch is set to heat, AC or off. ( I will have to double check one thing, but for the time being, assume that’s the case). Does this sound like a broken thermostat? BTW it’s a digital thermostat. I’m going to replace the batteries on it when I get home from work, but I don’t think that’s the problem.
One more thing, does any one know which wires I can jump to turn on just the fan? If I can jump the wires and ONLY the fan turns on, I’ll know it’s the thermostat that’s the problem, if the compressor kicks on, then I’ll know it’s most likely NOT the thermostat and probably the computer module in the furnace. Oh, and the termostat pops off the wall for easy access to the mounting bracket and has contacts on the back of it and the mounting bracket has a wiring harness like thing. So I can jump the wires without it being connected to anything. (Does that make sense?)
By any chance, is the 'stat set to “auto”? If it is, take it out of auto.
Assuming normal color coding, to engage the blower, you’d connect red to green. To “call” for cooling, the 'stat connects red to yellow. A good many 'stats will link the green and yellow wires together in the Auto mode, so if you connect red to either, you’ll have fan and cooling.
If the 'stat isn’t set to Auto, you may be better off calling a heating and air conditioning shop. The color code is more of a suggestion than a requirement, so there can be much confusion - might be a mis-wiring at the 'stat, especially if it’s a newer one that may have been put in by a weekend warrior.
What do you mean by that. The fan switch only has two settings AUTO (which means the fan turns on only when the AC or furnace ir running) and ON (which means it’s always running). So it get’s left in Auto most of the time. My problem is that when I turn it to ON, the AC compressor kicks on as well and turns the house into a freezer if I fall asleep with it on.
Firgured it out. Add to the list of dumbass things the previous homeowner did…Wiring the thermostat with his eyes closed.
I took a closer look at the wires and noticed the the yellow and green where reveresed, which makes sense for why I was having this problem.
Told ya the colors were just a suggestion to weekend warriors! Good to hear you solved the mystery.
I think the reason they were screwed up is that one of the wires was a different color, and he probably got confused, but still, it was only one wire that was the wrong color, the others all matched. Now, what I’m wondering is it my AC was running all winter everytime the furnace turned on?