Comfortmaker Runaway Cooling / Thermostat or Control Stuck

Comfortmaker air conditioner runs continuously and does not shut off even when set temperature is reached

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Thermostat stuck in cooling call, Shorted thermostat wiring (Y to R), Stuck contactor in outdoor unit, Indoor control board relay stuck closed

How to Fix / Troubleshooting

Safety: Turn off power at the breaker or disconnect to stop the unit before troubleshooting.

Steps:

  • Check thermostat: Turn thermostat to OFF. If unit keeps running, thermostat is not the cause.
  • Inspect contactor: With power off, check if contacts are welded closed. Replace contactor if they do not open freely.
  • Check thermostat wiring: Look for bare wires touching between R and Y at thermostat or air handler.
  • Board relay: If blower or condenser run with no call and contactor is free, the Comfortmaker control board relay may be stuck and require replacement.
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Repair Difficulty

Medium 3/5

Required Part

Contactor and Thermostat Wiring
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