Check for Power. Per Data Collected by ASM-air.com. Problem: Air conditioner or heat pump compressor will not start.I hear an “UGGG” sound for 5 to 10 seconds when the compressor tries to start then the compressor shuts off. AC Won't Work? The first and most obvious thing to do when your compressor won’t start is … If the replacements do not bring your HVAC compressor back to life, you have two options. When an AC compressor won’t turn on, the process can’t begin. A Dead HVAC Compressor. You may have a technician replace your compressor, or you may decide to replace the entire air conditioning system altogether. Freon After Freon has been compressed, it is circulated through this system while under pressure and it is passed … In this article we are going to look at some of the reasons why your Panasonic air conditioner has suddenly stopped working. Compressor replacement: $1150-$1520 (depending on size and type) Fan motor replacement: $210-$420; Refrigerant leak detection & repair: $227-$937; Circuit board replacement: $230-$610; AC compressor repair hard start kit: $100-$150 Here Are Some Average Air Conditioner Repair Costs . When refrigerant is still in the compressor, it is considered to be at the beginning of the air conditioning cycle.