Advice on mother's furnace not running for long.

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GrumpyDad

Minister of Fire
Feb 23, 2022
1,232
Champion, PA
Hi all. My mother called today telling me that her furnace runs for short periods of time then shuts off. This continues over and over. The large air filter was just replaced. I advised her to remove it entirely.
We have a serious lack of skilled trades people in my area. The ones that do show up will absolutely take advantage of the elderly and recommend a completely new furnace nothing less sadly. .
I have COVID right now unfortunately and am about day three in, coughing a lot and very dizzy. If push comes to shove I'll go over there wearing a mask but that's only so effective when someone is coughing. She is immune compromised so I'd like some ideas of things I can checklist to maximize my time while over there. Thanks .
Gas furnace
 
Sounds like a high limit switch kicking in, does the blower motor have bearings that take a drop or two of oil? could you provide some information on the furnace
We found someone recommended by a trusted retired hvac guy that will come out in a bit thankfully. Not that it is going to be that cold in the coming week, but with parts being in demand I want to get this behind us asap. I asked her for the model/make but she wasnt sure where to find that. I wish I could go over there and look for what might be flashing or any error codes. It would be very clear then.
 
Been awhile since I had worked on a gas furnace, but it sounds like either the limit switch or a bad/dirty thermocoupler. I also wouldn't rule out a clog or downdraft in the chimney/exhaust venting.
Just guessing at this point. Like I said it's been awhile...
 
Guy came out cleaned some dirt and it fired right up.
This morning same issue.
125 bucks for first visit. I'll bet there will be a cost for second. I will have to go over there
 
Sounds like an almost plugged heat exchanger to me.

Hard to diagnose it over the web, right? Good luck and keep your Mom warm!
 
I still have no idea what he did. He went back no charge thankfully and used a vacuum this time to clean it out. Mom said he was at it for a good bit, then tested it a few times.

Not sure if this is something that built up over the last say 4 years which was probably the last time they had someone out to check/clean it. Or, if this is a failing thermocouple or other problem that cleaning just masks the inevitable fix, likely at the worst time - when it's freezing out.
 
never pull your filter and run the unit that way. if you clog up your unit with dust there is no way to clean it but take the whole thing apart to do it.