Daikin Air Conditioner Error Code C5

C5 indicates an abnormality with the heat exchanger gas pipe thermistor in the indoor unit. The system has detected that the thermistor is either disconnected, shorted, or has failed, producing a resistance reading outside the acceptable range. The unit shuts down to protect itself until the fault is resolved.

No. The C5 error causes the unit to stop operating precisely because it cannot safely monitor heat exchanger temperatures without a functioning thermistor. Attempting to override or bypass the fault and run the system without a working sensor risks freeze-up of the indoor coil and potential compressor damage. The fault should be corrected before resuming normal operation.

Repair costs depend on what has failed. If the issue is simply a disconnected connector, a service call fee of roughly $75 to $150 may be all that is needed. A thermistor replacement typically adds $50 to $150 in parts, with total repair costs often falling in the $150 to $350 range depending on labor rates and access difficulty. PCB replacement is the most expensive scenario, potentially ranging from $300 to $600 or more including labor.

A knowledgeable DIYer can start by checking whether the thermistor connector has simply come loose from the indoor PCB, which requires no tools beyond removing the indoor unit cover. Testing the thermistor resistance with a multimeter is also within reach for those comfortable with basic electrical diagnostics. However, replacing the thermistor or PCB typically requires handling refrigerant-side components and should be performed by a qualified technician.

A power reset may temporarily clear the displayed error code, but C5 will return as soon as the PCB checks the thermistor circuit again during startup or operation. The underlying fault, whether a loose connector, failed thermistor, or damaged wire, must be physically repaired before the error will stay cleared.