This is rarely a problem with the refrigerant gas. It is almost always an electrical or wiring issue .
Disclaimer: Working with air conditioning systems involves electricity. If you are not familiar with electrical repairs, please contact a professional. o general ac error code 9c
The communication line fails to release voltage due to faulty resistors or tri-state buffers on the control board. This is rarely a problem with the refrigerant gas
For O General air conditioners, the 9C error code is a communication error that specifically indicates a mismatch between the indoor and outdoor unit PCBs o general ac error code 9c