HVAC Help

[SPDguns]

Any HVAC guys here? My gas furnace will randomly turn on, run for about a minute, then turn off. It happens several times a day and has been doing it for quite some time.

Other than that, the furnace runs correctly and heats the house fine. I put in a new non-programmable thermostat last week and it still does it.

I don't want to call out a service company because my system is old and they are going to tell me I need a complete new system at only a zillion dollars or $2000 a month for the rest of my life. I know eventually I will have to replace the system, but I would like to find out what the problem is first.

thanks!

 

[tyromeo55]

My best guess..... Google. ". Flame sensor"

 

[SPDguns]

My best guess..... Google. ". Flame sensor"

Flame sensor A.K.A. Thermocouple. I've checked the thermocouple and it's good. If it was bad, the system wouldn't work at all.

 

[Dirty Dave]

Circuit boards start acting funny when they are going out. It could be a limit switch also. You can look up the sequence of operation and try to trouble shoot it yourself. I wish you were closer I would look at it for you. But your probably going to have to call a technician out to actually figure out what it is. If its real old and the heat exchanger has cracks in it you need to replace it. There is to many things it could be to tell you exactly what it is over the computer. Board, limits, gas valve, draft motor, blower motor, ect....

I hope you get someone that treats you right and dont try to screw you. It happens all the time. But remember its not cheap to run a business either. The part may be cheap but he has to come to you, figure it out, gas, overhead, insurance, workmans comp, and years of training. That's what your paying for.

 

[SPDguns]

Thanks for the advice, I will try and at least narrow down the problem using your suggestions. I know I am less likely to get screwed if the technician knows I know what I'm talking about. I also don't mind paying for a good technician- the old adage " 50 cents for the cost of a part but 50 dollars for knowing which part". Thanks!

 

[plissken]

This just happened to me this morning! Heater kicks on, but doesn't engage the blower. A little chilly in the house this morning. Ugh!

 

[Viper16]

This just happened to me this morning! Heater kicks on, but doesn't engage the blower. A little chilly in the house this morning. Ugh!

Could be the starter contactor for the blower...cheap to fix, just be careful as the voltage is live on one side of it.

 

[Dirty Dave]

Capacitors store energy also. So even after you get it out it can still shock you. It is easy just be careful. You can youtube how to check its capacity. Assuming you have a volt meter.

 

[tyromeo55]

Flame sensor A.K.A. Thermocouple. I've checked the thermocouple and it's good. If it was bad, the system wouldn't work at all.

FYI. Flame sensor Is NOT the same as a thermocouple You gave very little info. With that little info I took my best guess


Eta.,,,

I'm not trying to be a jerk. I literally meant to google "flame sensor". The top hit is a YouTube video on how to check and clean a modern flame sensor.

Another "guess" would be a high limit sensor if the blower comes off and on

 

[Dirty Dave]

It sounds like an older model with a standing pilot? Model # of furnace??