How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Phil Your Own Question
Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
23932409
Type Your HVAC Question Here...
Phil is online now
A new question is answered every 9 seconds

My furnace will kick on and heat the house but the fan will

Customer Question

My furnace will kick on and heat the house but the fan will continue to blow and cool the house down. Have been having to go down and manually kill the power to get it to stop. When I turn it back on it will not come on until thermostat kicks the heat on but stays running again when heat on turns off. Decided to let it run with thermostat turned off and it did eventually turn off after about 25 minutes.
I did notice the air filter was very dirty. Thought I had replaced it recently but obviously not. Was wondering if you think the limit switch needs replaced.
Submitted: 27 days ago.
Category: HVAC
Expert:  WCohn replied 27 days ago.

Hello, my name is ***** ***** I look forward to helping you!

Expert:  WCohn replied 27 days ago.

This actually sounds like a thermostat issue

Customer: replied 27 days ago.
Have had two new honeywell thermostats that I tried. Same issue happening with each one.
Expert:  WCohn replied 27 days ago.

And was the fan setting set to AUTO?

Customer: replied 27 days ago.
Just a two wire system so has heat and off.
Expert:  WCohn replied 27 days ago.

Well, I'm going to opt out to allow another expert answer.

Expert:  Rick replied 27 days ago.

If the filter was very dirty then you could have had the limit open which would cause the fan to run on and blow cold air. But an open limit will typically shut the burner down before the thermostat is satisfied. Do you still have the same issue with a clean filter?