Good Afternoon from Florida!! I have a two year old Goodman Model GPC1242H41CA package unit that has heat strips, I had a short that eneded up causing me to replace the transformer and the control board. I ended up replacing the thermostat and wires as well and now the AC side works perfect but when it is changed to heat it blows the 3 amp low volt fuse and heat will not work. I replace the fuse and turn it back on to heat and it again blows the fuse….I dont understand why the cool works fine but the heat is blowing the fuse. I have checked the heat strips and nothing is broken or touching anywhere so I am kind of at a loss right now and could use some advice. Thanks!!!!!!
Goodman Model GPC1242H41CA Blowing Low volt fuse ONLY when heat is turned on
diy-vs-prohvaclow-voltagetroubleshooting
Related Solutions
I imagine you are referring to Heil Model N4H336GKE100.
Check the test control jumper on the defrost control board. In the "speed up" test position it will cause the timing you describe. For normal operation the test jumper should be OPEN (no jumper or metal object shorting the test pins together). The default for the timing jumper is usually "60." For dry climates the timing jumper should be "90".
The tech support manual is posted at this address:
http://icpindexing.toddsit.com/documents/086477/42804510201.pdf
Here is a snapshot from the relevant section:
If you have disconnected all external wires to the control board with only internal wires to the unit connected and the fuse still burns, that very likely indicates a failure of the board. With the fuse burning quickly, that often means a component in the power supply side of the board has catastrophically failed. To verify this, you could disconnect all wires to the board except for the power connection and the door switch and test to see if the fuse still burns in that condition (make certain you are using a correctly sized replacement fuse, obviously).
Replacing a board is typically not difficult if you can find a compatible replacement. Unfortunately, the wholesale price for these is often $200+ or higher.
Best Answer
My guess is there is a short in either the W wire or in one of the heating components. If it happens immediately it is probably in the W wire. If it goes for a while it is probably in one of the components and when that component is energized the fuse blows. Try disconnecting the thermostat wires from the unit and jump R to W. If it works your problem is in the thermostat or thermostat wires. If it stil blows the problem is in the unit itself. They do make things called poppers that are basically circuit breakers instead of fuses that fit where automotive fuses go. Saves a lot on fuses when not sure where the problem is.