The first and most obvious thing to do when your compressor won’t start is … 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. 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. Check for Power. In this article we are going to look at some of the reasons why your Panasonic air conditioner has suddenly stopped working. When refrigerant is still in the compressor, it is considered to be at the beginning of the air conditioning cycle. A Dead HVAC Compressor. Freon After Freon has been compressed, it is circulated through this system while under pressure and it is passed … Here Are Some Average Air Conditioner Repair Costs . AC Won't Work? You may have a technician replace your compressor, or you may decide to replace the entire air conditioning system altogether. 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 Per Data Collected by ASM-air.com.