Carrier · Air Conditioner error code
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Guide · Air ConditionerMost PTAC brands store fault codes that can be shown with a button combination on the control (for example, on GE Zoneline (2019 technical service guide) you hold FAN and the red AUX button together while the unit is OFF, and AUX clears stored faults; other models use other sequences, so use the model's tech sheet). Read the active code, fix the cause, then clear it.
Guide · Air ConditionerCommunicating systems use a four-wire bus: A and B carry data, C and D carry 24 VAC. Carrier's trade guidance says most faults come from the connecting wiring, so isolate devices one at a time before replacing boards.
Guide · Air ConditionerWork in order: line voltage at the motor plug, the command signal (24 V on a tap for constant-torque motors; board command for variable-speed), mechanical drag, and only then the motor windings versus the electronic module. Many 'bad motor' calls are a missing call or a bad ground.
Carrier · Air Conditioner
E1 / EL01
Indoor-outdoor communication error
Carrier · Air Conditioner
E3 / EH 03
Indoor fan speed out of range
Carrier · Air Conditioner
E4 / EH 60
Indoor room temperature sensor (T1) fault
Carrier · Air Conditioner
EC / EL0C
Refrigerant leak detection
Carrier · Air Conditioner
EH 02
Zero-crossing signal not detected
Carrier · Air Conditioner
F1 / EC 53
Outdoor ambient sensor (T4) fault