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Error Code
The E4 error code on your Carrier air conditioning unit indicates a communication error between the indoor and outdoor units. This communication failure can prevent the system from working properly.
If the wiring between the indoor and outdoor units is loose or damaged, it can cause a communication failure.
A malfunction in the PCB can disrupt communication between the units.
Voltage fluctuations or power surges can interfere with communication between units.
Turn off the air conditioner for 5–10 minutes, then turn it back on to reset communication.
Check for loose, damaged, or frayed wiring connections between the indoor and outdoor units.
If communication issues persist, the PCB may need to be inspected and replaced.
