5 Wire Thermostat Wiring Diagram. Orange This wire connects to your heat pump if you have one. This type of wiring is usually found in air conditioning systems or gas furnaces.
The yellow wire connects to your compressor. W White Wire to the W Term. This wire connects to your heat pump if applicable.
This wire connects to your heat pump if applicable.
If you have a C wire place it into the C terminal on your wall plate. HVAC systems with more functions need more wires to communicate to and from the thermostat. We have a 19-year-old condo with an old Carrier mercury thermostat. Always follow manufacturers instructions for both the thermostat and the HVAC system.