Upstairs HVAC System: On arrival, I turned the thermostat to cool mode and verified the indoor blower motor was running. I went outside and found that the outdoor heat pump was not running. Inspected the defrost board and found the board to have failed. I was able to test the outdoor unit and verified both heating and cooling operation. Went into the attic to inspect the electrical system and found the primary water safety switch has failed and therefore will not turn off low voltage power. Recommended replacement of the defrost board and installation of a new primary water safety switch. I installed a new outdoor defrost board and a new water safety switch at the indoor air handler. Installed new wiring terminal connections at the air handler to ensure a proper and secure fit. Tested all systems and verified operation. Everything is working at this time.