Comfortmaker Control Signal Interruption

Comfortmaker thermostat shows cooling call but outdoor unit does not receive 24V signal (no Y call at condenser)

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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

Broken low-voltage wire between air handler and condenser, Float switch open due to full drain pan, Blown 24V fuse on indoor board, Faulty thermostat or wiring

How to Fix / Troubleshooting

Safety: Turn off power to indoor and outdoor units before working on low-voltage wiring.

Steps:

  • Check float switch: If equipped, ensure condensate pan is not full and float switch is not open. Clear drain and reset.
  • Inspect low-voltage cable: Look for breaks or damage between indoor and outdoor units.
  • Test 24V at Y terminal: With a meter, verify 24VAC between Y and C at the air handler when cooling is called.
  • Check fuse: Replace blown low-voltage fuse on Comfortmaker board after correcting any shorts.

Note: Persistent control issues may require a technician to trace wiring and controls.

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Repair Difficulty

Medium 3/5

Required Part

Low-Voltage Control Wiring and Float Switch
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