Hello there, I have a Rheem furnace and is only one year old. Recently my furnace didn't come on so I had someone come out and look at it and it turns out it was the defrost board on the heat pump that was bad. I replaced the board with a new one and turned the system on and it worked on heat and air conditioning settings. I had it off for about two weeks because I wasn't using it due to the nice weather,However I went to turn air conditioning on and it wasn't coming on at all again. It keeps blowing the fuse on the furnace which tells me that the defrost control board is making the fuse blow again. My question is if I replace the defrost control board on the heat pump (outside Unit) and it keeps blowing my fuse what could be wrong and what do I need to replace?
By the way I have a dual fuel system, electric and propane so I had been using the system on propane only by having the defrost board disconnected and putting the thermostat on emergency heat only. Please help.

The defrost board is controlling mostly low voltage. I can not se how this would be blowing your furnace fuse. Try replacing the fuse and just turn on the fan and see if it blowes