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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Every time i turn thermostat to heat it blows fuse in unit

Customer Question

every time i turn thermostat to heat it blows fuse in bryant unit
Submitted: 10 months ago.
Category: HVAC
Expert:  Kcrand36 replied 10 months ago.

good evening, I am Kevin from Ja.......

can I get the model # ***** your furnace?

Customer: replied 10 months ago.
fb4cnf030
Expert:  Kcrand36 replied 10 months ago.

do you have a heat pump or electric heat?

Customer: replied 10 months ago.
electric heat
Customer: replied 10 months ago.
its the 3 amp inline fuse on the red wire thats hooke to the thermostat wires
Customer: replied 10 months ago.
as soon as the thermostat clicks by either turning the switch to heat with the desired heat setting set above room temperature or by raising the desired heat it blows
Expert:  Kcrand36 replied 10 months ago.

you could have a defective contactor or relay. the coil could be shorted causing the blown fuse.

Customer: replied 10 months ago.
how can i trouble shoot that?
Expert:  Kcrand36 replied 10 months ago.

first thing I would do is shut off power to electric heat, pull both wires off coil and check the coil with ohm meter from coil to ground, if you have any continuity, replace the contactor.

Customer: replied 10 months ago.
My mistake on the electric heat or heat pump. It's a heat pump. Can incorrect fan settings on the thermostat blow the fuse link in the red wire?
Customer: replied 10 months ago.
Could a bad thermostat cause the fuse to blow?
Expert:  Kcrand36 replied 10 months ago.

I know this is probably NOT what you want to do, but try it on AC, It could be the contactor out in the condensing unit for the compressor. If it works in AC, that is probably not the case.