I had another HVAC company look at my heat pump in the spring and they couldn't diagnose the problem. They replaced a contact and some other parts, guessing that the parts may have been the problem, but they weren't. I spent hundreds of dollars for that visit and it didn't fix the problem (my heat pump would try and start, but then would shut off.) I left it off all summer and not wanting to pay high utility bills for heating season, I called Stacy. The Stacy technician did a thorough troubleshooting and diagnosed a faulty low pressure switch. The refrigerant pressure was correct, but the switch did not function properly. Stacy obtained a replacement part and returned the next business day and finished the repair. Replacing the old switch required that they cut out the old switch, braze in the new switch, hook up a vacuum pump, and then recharge the system. Everything works fine now.