I have a 3 Ton Bryant package heat pump that is popping the 3A fuse. It will run for about 10 minutes when cold before popping the fuse. Once the unit is "warmed" up, it immediately pops the fuse when I reset it.
I have a secondary fuse box outside that has 30A, 40A, and 60A circuit breakers. Whatever is causing the issue is tied to the 40A breaker. When I reset the 3A and click the breakers back on outside, only the 40A causes the 3A to pop.
I have already replaced the thermostat inside, as well as ran new 18 gauge from the thermostat to the heat pump.
I don't really see any burn marks on the inside of the door. The 3A pops even when the door is off, so I don't think it has to do with contact with the door. I couldn't see a spark anywhere when the 3A pops.
I do know how to use a multimeter but I don't know where to or how to trace a short in an HVAC system.
I'm hoping a training eye might see something that I clearly don't. I have the service manual pdf but I think it was too large to upload to here.