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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Working on a PTAC unit that keeps blowing the circuit board

Customer Question

working on a PTAC unit that keeps blowing the circuit board fuse ! I have by passed & the compressor runs fine @ correct amperage ! I have tried to find anything that goes to ground & have not found anything ! I bought & replaced the board & its fuse blew as well !
Any suggestions ?
Submitted: 2 months ago.
Category: HVAC
Expert:  Phil replied 2 months ago.

Hello, there is an *intermittent short in one of the peripheral devices that plugs into the board, very very difficult to locate ... as most of the time the defective device will checkout OK when you test it.

This is why we have so many older HVAC techs with no hair.

Suggestion, wiggle each wire individually, with tweezers, so you do not bump any adjacent wires if you can do this with the unit running, when you cause a short the fuse will blow.

Stay in touch without a time limit as needed.

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