How to Test a Home Thermostat

Pinpoint heating and cooling problems.

Home thermostats turn on your heating or air conditioning unit when the home reaches a pre-determined temperature. Figuring out if your home thermostat is malfunctioning can save you calling a service technician. By following basic procedure, you can check the thermostat to determine if any heating or air conditioning problems lie with the thermostat or elsewhere with your system.

Things You'll Need

• Screwdriver
• Small level
• Small brush
• Jumper wire kit

Instructions

1. 

   Turn off both the thermostat and the furnace. Cutting power to both will eliminate any electrical safety issues.

2. 

   Remove thermostat cover from thermostat. Remove thermostat from wall. Check that all wires on the thermostat are tight (four or eight wires are common). Be sure the thermostat unit is clean and dust-free. Use a small level to ensure unit is level when in wall. Unlevel thermostats can malfunction. If leveling must be done, If leveling is needed, adjust mounting screws. Use brush to clean all wires and pieces.

3. 

   Remove wires from the thermostat. Make sure you have enough wire exposed after unscrewing each wire so that it will rest outside the thermostat hole in the wall.

4. Use jumper wire kit to test thermostat. Connect insulated jumper wire to the red and white terminals on the thermostat. Turn the power to the furnace back on. If the unit pops on, the thermostat is faulty.

5. Reconnect wires to thermostat and re-set thermostat in wall. Replace thermostat cover. Check the fan to make sure it is reconnected properly by turning power button on thermostat to "on." Turn fan "on." If fan kicks on, it is properly reconnected. Turn mode to "Auto" and put thermostat cover back on unit.

Tips & Warnings

• Use caution because thermostats and their wires are fragile.

References

• Honeywell
• Best Thermostats