Display shows F7, and the unit may not respond to the thermostat or remote.

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.

Possible Causes

Loose thermostat wiring at the air handler, incorrect thermostat type or configuration, faulty Comfortmaker communicating thermostat, defective indoor control board communication port.

How to Fix / Troubleshooting

Safety: Turn off power to the air handler and thermostat (if powered from the unit).

Steps:

Verify thermostat type: Ensure you are using a compatible Comfortmaker/ICP communicating thermostat if the system requires it.
Check thermostat wiring: Tighten all low-voltage connections at the thermostat and indoor unit. Ensure no wires are shorted.
Inspect cable: Look for damage to the thermostat cable between the wall and the air handler.
Reset thermostat: Follow the thermostat manual to reset to factory defaults, then reconfigure for your Comfortmaker system.

Note: If F7 persists with a known-good thermostat and wiring, the indoor control board may be at fault.

Repair Difficulty

Medium 3/5

Required Part

Communicating Thermostat

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