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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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2 Goodman HVACs 5ton & 3 ton quit working. Power into unit

Customer Question

2 Goodman HVACs 5ton & 3 ton quit working. Power into unit is fine. turn down the tstat and I hear a hum but no fan kicking on. Both at once is too coincidental. Capacitors fried by electical surge or circuit board. How do I test the circuit board?
Submitted: 2 years ago.
Category: HVAC
Expert:  Phil replied 2 years ago.
If you got a 120 volt reading to ground on each leg of the power, then it is likely that only ONE leg is hot and that the other leg is reading 120v because of what we call 'feed back'. If you got a 230v read *between* the two legs of power, then indeed it would be quite a coincidence, that both circuit boards blew. To check the circuit boards, look for a 3 amp automotive type fuse on each board, replace it if its blown, if the fuse is OK look for burnt spots on each side of the board... if you see any over heated brown spots or burnt spots the board is bad for sure. So far however I suspect you have one leg of the 230V power out, verify that first. We can go from there..