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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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The furnace keeps blowing the fuse. A new electric starter

Customer Question

The furnace keeps blowing the fuse. A new electric starter was installed last year. It's a gas furnace. It;s worked fine until now. It blows the fuse everytime I try to start it.
Blowing as soon as I put the fuse in , even with the switch in the off position.
Should we trying a higher amp fuse?
Submitted: 11 months ago.
Category: HVAC
Expert:  Rick replied 11 months ago.

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. First I’ll need some more info so I have a more complete picture of you situation

Where is this fuse? What is the brand and model number of your furnace?

Customer: replied 11 months ago.
Bussmann 15 amp fuse
Expert:  Rick replied 11 months ago.

So it's on the circuit feeding the furnace not in the furnace?

Customer: replied 11 months ago.
Right..the single fuse outlet is on the furnace itself
Customer: replied 11 months ago.
The other circuits feeding the house are all ON and WORKING
Expert:  Rick replied 11 months ago.

Ok so you have a short somewhere in the furnace wiring. Tracking it down can be a challenge. The first thing to do is check the wiring inside the box where the fuse holder is mounted. Make sure there are no bad connections (hot to ground or neutral). Is this an oil fired or a gas fired furnace?

Customer: replied 11 months ago.
Gas fired furnace
Expert:  Rick replied 11 months ago.

Ok, once you check the wiring in the box the next step would be to disconnect the major components in the furnace; the main blower, the draft inducer fan (if it has one), does it have a control board or a fan center relay (disconnect the power to either one or both). Once all the components are disconnected try a new fuse. If it blows again then you have a short in the wiring. If it doesn't then re-connect the components 1 at a time starting with the board or the relay until you find which component blows the fuse.

Customer: replied 11 months ago.
Looks like the little silver pin in the fuse receptacle is burned
Expert:  Rick replied 11 months ago.

That could just be due to the short and if you screwed the fuse in while the circuit was hot. It would be a good idea to replace the receptacle and if it doesn't have a service switch right there now would be a good time to install one. You should screw the fuse in then turn the power on. A switch right there would make this a lot easier