Heat Pump Thermostat Wiring Chart Diagram – HVAC Heat Pump Thermostat Wiring Chart Diagram - HVAC - The following graphics are meant as a guide only. Always follow manufacturers instructions for both the thermostat and the HVAC system. Additional articles on this site concerning thermostats and wiring can help you solve your problem or Heat Pump Thermostat Wiring Diagram Heat pump thermostat wiring - A typical wire color and terminal diagram. As shown in the diagram, you will need to power up the thermostat and the 24V AC power is connected to the R and C terminals. The color of wire R is usually RED and C is BLACK. C is known as the common terminal. How to Wire a Goodman Heat Pump | Hunker In the Goodman heat pump there are two wiring sources that have to be connected. These two sources are high voltage and low voltage. High voltage is the voltage the unit needs to run. Low voltage is the voltage that is used to control the unit from a thermostat or other controlling device.