Heat pump wouldn't go into defrost Verified defrost thermostat closing correctly Swapped defrosr boards Still wouldn't go into defrost Found R wire not getting 24V at the heat pump Opened air handler, red wire going to heat pump was not making good connection under the wire nut Made sure all the wires were inserted equally and tight under the wire nut Unit now going into defrost properly Put old defrost board back in the unit System is defrosting properly with the old board We will keep the new board for a future call