PJmax, thank you for your help, I look forward to using this site more for more DIY stuff and getting good advice. Not sure what signal was being sent from the AH to the HP around the 3 - 4 minute mark but it was being shorted to ground and blowing the fuse. And actually working better now that the aux heat actually works. Ended up getting a "free" transformer out of the deal but all together spent a grand total of $236 and my heat is working again with no famous blown 3 amp fuse.
Out the door I ended up paying $51 for the contactor relay and DCB another $36 for the solenoid coil (all replaced by me) then $49 for the service call and $100 for the Low Voltage Wiring Repair. Obviously he attempted to up sell the repairs and sell me a maintenance package which I kindly declined but I do know what company to call if I find myself in a bind again.
GOODMAN HEAT PUMP DEFROST BOARD TEST CODE
Additionally they pointed out multiple issues with my new construction home with brand new HVAC system including: a small refrigerant leak, strip emergency heaters not connected at all (which checks with chart due to not having heat when set to emergency) and no float switch installed on the condensate overflow pan (required by code for attic installed units from what he said).
They did not mention a specific location of the short, they just swapped to a spare wire. (It was the red wire going from the air handler to the heat pump). The amplifying condition was that the short was only noticed after ~3 mins of heat pump operation and I never did any clamp on ammeter checks during operation. The issue was a shorted to ground low voltage wire (one of the wires I had checked). Finally he came in and he said that they think they found the problem. Anyway, he had to call in reinforcements, another guy showed up and they spent 5 hours going up and down from the attic to the heat pump and back again. Surprise surprise, what happened? He fried my 24v transformer and replaced "for free" because he caused the failure. Guy came out and popped in a 5 amp resettable breaker instead of the 3 amp fuse :NO NO NO:, I made a comment about the higher current possibly damaging something but he assured me that he has never seen anything like that happen before. (PJ, you mentioned the new coil should be about 30 ohms, old one read 14 ohms and new one read 16 ohms, just passing on that info.) I was running out of parts and ideas to throw at this thing so.I called a shop. I believe that I was using the audible continuity indicator on my multimeter and did not pay attention to the actual resistance reading, so I thought I found my short to ground, WRONG. Well, I installed a new reversing valve solenoid coil and had the same problem. Thanks in advance, sorry for such a long post. Should the solenoid not be completing the circuit right now? Is the reversing valve solenoid bad or possibly just stuck? Any help would be greatly appreciated. This tells me that the solenoid is completing a path for current flow from O-rv to C-rv. Reading C-rv on the DCB to ground is a short (just a common line I'm guessing). The black wires for the reversing valve solenoid go to terminals O-rv and C-rv on the DCB. Pulled the 2 black wires for the reversing valve solenoid from the control board and the solenoid itself is not shorted to ground although the reading across the solenoid is zero. The O terminal is tied to the O-rv terminal (reversing valve) on the control board. I disconnected the orange wire from terminal O and the short to ground was on the board. Orange wire goes to the defrost control board (terminal O).
Disconnected the orange wire at the heat pump and the short to ground was on the heat pump side (not the house side). Finally I disconnected all low volts wires at the air handler and tested individually to ground and found a short to ground on the orange wire. Replaced the defrost control board (PCBDM133) and retested, blew the fuse. After reading some other posts, I checked the contactor in the remote unit, it cycled normally and coil read no continuity to ground but I replaced it anyway. (Goodman ARUF48D14AC air handler and VSZ140421AA heat pump) On the chance it was just a bad fuse, I replaced it and it blew again after approximately 3 mins of air handler and condenser operation. This is a split unit with a remote heat pump outside. As the title states, I have a blown 3 amp fuse on the control board located in the air handler. Well I've looked and can't seem to find the answer I'm in search of so here goes.