# 5 Amp fuse blowing



## chitownken (Nov 22, 2012)

Does it blow the fuse it you turn the fan to ON but leave the system set on HEAT?


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## HVACTECH96 (Oct 16, 2012)

Try removing Low voltage wire for condenser ,inside the furnace.R &Y.If fuse still blows , problem is inside the house.Usually find a short where low voltage wire exit the furnace cabinet, and has been rubbing on metal edge.If fuse doesnt blow the the problem is between furnace and condenser.Bare spots where critters have chewed wires is common.


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## jfrotten (Aug 14, 2011)

You're over-thinking it. You have a low voltage short somewhere. Take the thermostat off of the wall. Take the red wire and touch it to each of the other wires one at a time for a few seconds and see which one blows the fuse. DON'T TOUCH RED TO BLUE. This WILL blow your fuse because blue is your common. Once you know which wire you're dealing with you usually have one or two spare wires like brown or black depending on your setup. Swap out the shorted wire and you'll be back in business.


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## hvac instructor (Jun 8, 2012)

check the actual contactor. i had one that the coil was shorted to the mounting base. everything was fine untill the contactor pulled in.check for short on coil to the mounting base. i saved that contactor and use it in class.


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## KingPin461 (Jun 21, 2012)

Hey guys, sorry for the late reply...been outta town for a few days. I was able to fix the problem...:thumbup:

I decided to disconnect the low voltage wires for the condenser from the air handler control board to see if the problem was inside the house or outside. When I set it on Cool, the fuse didn't blow this time. 

I reconnected the wires at the board and disconnected them outside at the condenser to isolate the contactor. This time, the fuse did blow again. 

I ended up running a brand new line from the air handler to the condenser outside....problem gone. Wanted to thank all of you for your suggestions and input!


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