Abstract: An integrated heat pump and electrical heat control (12) has thermostat signal inputs (O, W1, W2, G, Y) along with a defrost sensor input (DF_IN). The defrost sensor (22) is located in an outdoor unit (4) which also includes a compressor contactor (CC), condenser fan (16) and reversing valve (18) relays (K4, K3, K2) controlled by micro-controller (U1). The normally closed condenser fan relay (K3) is energized through the defrost sensor forming a hardware lock-out in which the defrost sensor contacts must be closed for relay (K3) to be actuated de-energizing the condenser fan. The compressor contactor (CC) is energized through a low pressure switch (24) and high pressure switch (26) forming another hardware interlock. The evaporator fan is energized by relay (K1) controlled by micro-controller (U1) and matched to the compressor for improved efficiency and comfort.