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My carrier evaporator keeps on blowing the 3 amp fuses. I…

Customer Question
My carrier evaporator keeps...

My carrier evaporator keeps on blowing the 3 amp fuses. I already replaced the capacitor, contactor and lastly the transformer. You think that I have wires sticking together?

Contractor's Assistant: I'll do all I can to help. How long have you been dealing with this?

For about a week now, luckily, I have 2 units.

Contractor's Assistant: Did you double-check the thermostat? And what about the unit's filters?

Filters, good but the thermostat is one of those Carrier Performance Edge but when I removed the thermostat from the wall, it fell off and the wiring harness, which is a small plastic part with two wires in it. The wires came off.

Contractor's Assistant: Do you plan on doing the work yourself?

Yes. I am EPA and TDLR in the state of TX.

Contractor's Assistant: Anything else we should know to help you best?

Do I replace the wiring harness or do I do a visual inspection of the thermostat wire?

Submitted: 10 months ago.Category: HVAC
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Answered in 35 minutes by:
10/10/2017
HVAC Technician: Phil, Mechanical Engineer replied 10 months ago
Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 7,426
Experience: Retired HVAC/ Electrical & Boiler contractor. Industrial
Verified

Hello, yes it is likely that you have two of the 24vac control wires stuck together or a bad printed circuit board.

Tell me if the fuse was blowing before you did all of those parts replacements, or after you did those replacements.

.

We can go from there without a time limit

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Customer reply replied 10 months ago
The outside fan wasn't on so he, the home owner, replaced the contactor. He then noticed he didn't have 24 volts to the thermostat. He then called me over. I checked the capacitor, which was bad and I changed it out and I went to the evaporator and noticed that the 3 amp fuse was blown. I changed out the fuse and went to the thermostat and noticed,that it was 2 different gauge of wires connected.
HVAC Technician: Phil, Mechanical Engineer replied 10 months ago

Thanks, ***** ***** an untrained home owner elects to just start changing out parts, often wiring mistakes are made, and you will not know which wiring mistakes, but you will notice the blown fuse.. And that is where you are on this situation.

There is never, ever, 24volts measurable at thermostats without a C wire attached, most do not have a C wire, so that red 24vac + wire can be hot, but it will not read with any voltage, so then on that basis the home owner makes more changes and possibly introduces more mistakes... then when you arrive you have no idea on earth what was done or correctly or incorrectly.

.

attach a photo of the thermostat wires shown connected to the thermostat, and the same wires where they attach inside the furnace or air handler, and a photo of the wiring diagram glued to the inside of the blower access door, and I will prescribe a few tests.

.

Use the 'add files' link next to your send button to get those photo's to me, they must be exceedingly well lit and focused

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Customer reply replied 10 months ago
Ok, I will.
HVAC Technician: Phil, Mechanical Engineer replied 10 months ago

Use the 'add files' link next to your send button in this dialog box to get the photo's to me, we can go from there.

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