Comfortmaker
No Power / Control Circuit Failure
Comfortmaker system will not start at all; no indoor or outdoor operation
Advertisements
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.
Advertisements
Possible Causes
Tripped main breaker, Blown low-voltage fuse on indoor control board, Broken thermostat cable, Faulty thermostat, Open transformer
How to Fix / Troubleshooting
Safety: Use caution when working around live circuits. Turn off breakers before removing panels.
Steps:
- Check breakers: Verify both air handler and condenser breakers are ON. Reset once if tripped.
- Inspect low-voltage fuse: On Comfortmaker boards, look for a 3–5A automotive-style fuse. Replace if blown, but investigate shorts in thermostat wiring.
- Test thermostat: Ensure display is on and set to COOL. Replace batteries if applicable.
- Bypass thermostat (advanced): With power off, temporarily jumper R to Y and G at the air handler to see if system starts when power is restored. If it does, thermostat or cable is suspect.
- Check transformer: Measure 24VAC output from transformer. Replace if no output.
Call a technician: If fuses keep blowing or no 24V is present, professional diagnosis is needed.
Advertisements
Repair Difficulty
Medium
3/5
Required Part
24V Transformer and Control Board Fuse
Check Price on Amazon
We may earn a commission from links on this page.
Advertisements