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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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GPH1448H41 goodman 4 ton heatpump package compressor/fan not

Customer Question

GPH1448H41 goodman 4 ton heatpump package compressor/fan not engaging, 240v at contactor input
reading 120v on each leg of contactor output but 0v nothing, natta zip whenvoltage is read across the two output terminals
contacts quite black
coil is not engaging when thermostat engaged
reading 240vac at coil
transformer 240vac input read across common and 240 terminal
24v output is reading 240vac across the 2 output terminals
blower fan is cutting on and blowing air through ducts but only hot air
Bad contactor, bad transformer or both, had plans on pulling output wires off of transformer but lost day light
Submitted: 1 year ago.
Category: HVAC
Customer: replied 1 year ago.
capacitor tested good but slightly out of tolerance so change with newwhen you engage coil manually compressor and fan comes on
Expert:  Brian HVAC Guy replied 1 year ago.
Hi I'm Brian and I'm here to help! First, can you please clarify the following sentence?:"24v output is reading 240vac across the 2 output terminals" Are you actually reading 240 volts (and not possibly 24.0) between the two 24 volt terminals on the LOAD side of the transformer? There should be Red wire(s) on one terminal and Blue wire(s) on the other. Thanks, -Brian
Customer: replied 1 year ago.
240 volts on the input and output of the transformer....cant verify colors right now but has not been worked on until now
tested across com/240 on the top of the transformer and across the 24volt outputs on bottom.....also seeing 240 at coil
on contactor.
Customer: replied 1 year ago.
should be as it shipped from factory except the change out today of cap.....
Customer: replied 1 year ago.
if I checked each line to ground which I know is not accurate testing
I got readings of approx. 120 on each output terminal and was no decimal
had on 200 v ac setting on meter and overloaded and had to switch to 500.....
Expert:  Brian HVAC Guy replied 1 year ago.
Thanks, ***** ***** the diagram I would have to suspect the transformer did a total meltdown internally. That's a very odd and rare failure though. I just can't see where anything else on the low voltage side could net you 240 on the transformer's (or contactor coil's) 24 volt terminals. An easy way to tell would be to disconnect the load leads and ohm them out to the line leads. There should be infinite resistance between the line and load windings (between any line terminal and any load terminal). Under normal circumstances if the transformer was moist you may get a low megohm reading but that should be it. I'm shocked that the line voltage is passing all the way through to the coil on the compressor contactor! I would not put power back to that machine until the high on low voltage issue is figured out! I'd look very carefully at all the wiring in the unit to make sure nothing has melted somewhere else causing this. If it does turn out to be the transformer, I would be very surprised if there wasn't something else burnt in the low voltage circuit! I can almost guarantee the compressor contactor is also burnt! You can check that with a resistance test across the coil terminals (with one coil connection disconnected), I bet it shows OL (open). I'd be very surprised if the defrost control board isn't burnt as well. Let me know what you get for the resistance reading from line to load terminals on the transformer and we can go from here. Thanks, -Brian