3 Amp Fuse Blowing When Calling for Heat or A/C

Hi everyone - the 3 amp fuse inside my air handler is blowing when the system calls for heat or a/c from the outdoor heat pump. I can run aux heat without any issues. It is a Goodman heat pump, about 9.5 years old.

From what I’ve read, this is likely a bad contactor coil or reversing valve coil. I have visually inspected the thermostat wiring and I don’t see anything that could be causing a short.

My questions are:

- do you agree that those are the most likely culprits? Any other likely causes I may not be reading about?

- I’m a fairly confident DIY’er and I’m confident doing basic electrical work. If in fact it is one of these components, would you recommend DIY repair or should this be left to a pro due to risk of further damage to the system?

Thanks!