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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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My Honeywell thermostat just went blank and my heat turned

Customer Question

My Honeywell thermostat just went blank and my heat turned off. Any suggestions? It's not battery powered and I already checked the cuircuit breaker
Submitted: 1 year ago.
Category: HVAC
Expert:  airheatman replied 1 year ago.

Possibly a blown fuse in the furnace ot air handler. Most have a small 3 or 5 amp auto type fuse on control board.Let s start there


Customer: replied 1 year ago.
I replaced it, the heat came back on and then the fuse blew again about 30 minutes later. Any idea on what could be blowing the fuse?
Expert:  airheatman replied 1 year ago.

If fuse blew again we have to have a short somewhere. Tell me about your wiring at thermostat.hat color wires went to what terminals on old thermostat and where do you have them on new?

Customer: replied 1 year ago.
I don't have a new thermostat. I've lived in this house for 18 months and nothing's changed recently. The heat was on working fine so far all winter and last, and now for some reason the fuse keeps blowing. The only unusual thing is I live in MD and there's a blizzard outside, but I'm not sure how that could impact the wiring
Expert:  airheatman replied 1 year ago.

Cold should not effect anything that would cause the short.Lets do this.Disconnect thermostat wires at furnace board.Then connect the R and W terminal on board together and see if heat works or if fuse blows.If heat works this way, we know short is external from furnace in wiring or thermostat.If fuse still blows most likely a shorted furnace board.