Came home from lunch today and blower motor for furnace is running even though it’s fifty degrees outside. Doesn’t stop blowing when themostat is turned to off only when manual switch inside furnace closet is switched off. Got any ideas where to start?
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Bad/old tstat battery, had some similar weirdness with the furnace running when it wasn't supposed to awhile back.
PJ
Completely removed t-stat from wall to disconnect since it is programmable one. Blower keeps on a running with no t-stat hooked up.
You could also have a bum limit switch inside the furnace. It normally keeps the blower running after the burner stops to dissipate the remaining heat in the burner. If the limit switch is broken, it can keep the blower running for ever. The thermostat will keep turning the burner on and off though.
Do these limit switched even stick open?
I tapped out my expertise on my first answer, so I'm not sure if it can be stuck open.
Stupid question, your thermo should have a switch on it that reads On/Off/Auto. Where is that switch set?
Doesn't matter runs no matter where it is set on, off auto, cool , off or auto.
Stuck fan relay?
I had a problem with blower that was short cycling. I traced it to a circuit board called a "blower control". Replacement control cost me $65 and about an hour to replace. My furnace is a Lennox. I don't know if others are similar. If you open up the unit there is usually a circuit diagram that you should be able to follow. Obviously, if you don't feel comfortable with this stuff you should call a pro. Good luck.
Hey, spring is almost here. Then you can turn the power off and deal with it in the fall."With every mistake we must surely be learning"
And how will the cold a.c air circulate this summer?
Hey, I can't solve all of your problems. When it gets hot out just sit back and have a beer."With every mistake we must surely be learning"
If this is a conventional furnace then the fan/limit switch. If "advanced" furnace then your control board may be fried ($$$).
happy?
That's funny, I had the same problem two nights ago- temperature goes down at ten-thirty or so, when I went to be around midnight I noticed the blower was still on. I looked at the thermostat, the batteries were still ok- I flipped the breakers for the furnace, flipped them back on, and it's worked fine ever since.
zak
That's typically due to a fault detected in an HE furnace -- lack of airflow in burner, lack of ignition, etc.
If ignorance is bliss why aren't more people
happy?
Looks like a call to the service guy is in order. Left it running last night figgered it would pump out right when the frunace kicked on but it didn't. now the furnace doesn't kick on when it should. SWMBO observed that she did switch the t-stat over to cool a few days ago when it got near 80 here so that probably let the gremlin in the system.
T-stat may have been miswired prior to switching to cooling. The way the fan is wired between furnace and AC is a little funky.
If ignorance is bliss why aren't more people
happy?
It worked o.k. last summer. Cripes you telling me the black choppers are coming in and rewring my t-stat while I'm at work?
No black choppers exist. Ignore the new camera and microphone holes in your existing thermostat; they have always been there. ;-)
Seeking perfection in an imperfect world is a fool's errand. Making something look perfect is a whole 'nother story . . . .
It's possible something has becomed mucked up with the wire to the AC compressor unit.
If ignorance is bliss why aren't more people
happy?