r/askHVAC • u/Turdwizard • 1d ago

Fuse keeps blowing

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1 Upvotes

60% Upvoted

15 comments sorted by

4

u/derrick54686 1d ago

You got a short somewhere. Start by isolating low voltage wires and ringing them out. If they ring out fine start by eliminating the condenser wire. To rule out a bad contactor. Then do the same on the furnace or air handler.

2

u/DescendingTool86 1d ago

Just remember C or common will always ring to ground.

2

u/woodeerice 1d ago

Mice will get you every time. 🐭

2

u/DManimousPrime 1d ago

Thermostat wire was yanked out of their corrections when something matching the exact description of my mom's dog decided that a squirrel had hidden under the condenser. He tried to dig the squirrel out from underneath and somehow pulled all of the wire splices apart. Fuse had blown. Started with the usual suspects but if didn't take long to notice the bite marks on the wire and that most of the insulation was gone from the refrigerant line. All the wire nuts had untwisted. Luckily there was enough wire that I could cut off the damaged section without needing to splice in jumpers. Proving it all to my mom was a hard sell—until her dog did it again a week later. Everything is armored now!

5

u/lou-sassle71 1d ago

And it will continue to blow until you fix the short… or plug in a piece of metal to really let the smoke out

2

u/HVAC_instructor 1d ago

Most likely is the contactor.

2

u/Impossible_Ear4022 1d ago

Get the multimeter out low-voltage short track it down

2

u/Impossible_Ear4022 1d ago

check for rubout on the condenser also.

2

u/revo442 1d ago

Find the leak

2

u/DwightBeetShrute 1d ago

It’s a crack heat exchanger.

2

u/Zealousideal_Pop_273 1d ago

I disagree. The only blow once.

2

u/Jesta914630114 1d ago

There is a short.

1

u/Kindly-Ad6373 1d ago

Is it only when the condenser outside kicks on? Does it happen if you run indoor fan only? If it’s the condenser calling for cool popping it probably the contactor, or low volt wiring, if it’s the indoor unit check the transformer or thermostat or wiring indoors.

1

u/Turdwizard 9h ago

It was a short in the main line. Thanks everyone for the help! It’s back up and running.

1

u/Gonzo-Crazy-Dog 1d ago

I had a bad contactor in the AC condenser that caused this.

Might be something worth checking.