Troubleshooting The Wiring of a Honeywell Thermostat

Ignore wire colors when making determinations.

Honeywell uses standard HVAC (heating, ventilation and air conditioning) abbreviation conventions for wiring in its thermostats. The key to troubleshooting a Honeywell thermostat's wiring is to know which abbreviations relate to specific pieces of HVAC equipment. You can then attach the correct wires from the equipment to the right terminal on the thermostat. This will ensure proper functioning of the specific equipment; for example, turning the heater on will not turn the air conditioning on.

Instructions

1. Open the cover of the thermostat and take a look at the terminals. You will see that they are marked with abbreviations called "Terminal Letters."

2. Refer to the following industry-standardized abbreviations: C is the common wire from the secondary side of the cooling transformer; Rc is the cooling power, connected to the secondary side of the cooling system transformer; R is the heating power, connected to the secondary side of the heating system transformer; W is the heat relay (stage 1); W2 is the heat relay (stage 2); Y is the compressor contactor (stage 1); Y2 is the compressor contactor (stage 2); and G is the fan relay.

3. Trace back the wiring from the specific equipment to the thermostat and make sure the correct wire is connected to the correct terminal. For example, "W" is the wire from the Stage 1 heat relay and it should be connected to the terminal marked "W" in the thermostat.

Tips & Warnings

• Ignore wire colors when making determinations. Don't connect wires to terminals marked "Not Used."

References

• Honeywell Prestige Digital Thermostat Manual