Mitsubishi Air Conditioner Error Code TH

The TH code means the electronic thermal relay function has detected that the cumulative thermal load value has reached or exceeded 85% of the threshold set in parameter Pr.9. It is a pre-alarm warning, meaning the system has not yet tripped into full fault mode but is approaching its protective limit. The code is designed to give you time to investigate and correct the cause before a full shutdown occurs.

The TH code is a pre-alarm warning and does not represent an immediate shutdown condition, but it does indicate the system is under significant thermal stress. Continuing to operate without addressing the root cause risks escalating to a full thermal trip fault, which could potentially damage the motor or compressor over time. It is advisable to reduce the load on the system and investigate the cause promptly rather than ignoring the warning.

Repair costs vary widely depending on the cause. If the fix is simply adjusting the Pr.9 parameter or cleaning filters and coils, a service call might range from a modest diagnostic fee up to a few hundred dollars for labor. If the motor or compressor has sustained damage and requires replacement, costs can range from several hundred to over a thousand dollars including parts and labor. Getting a diagnostic inspection is the best way to determine the actual scope of the repair.

In some cases, yes. If the cause is a dirty air filter, blocked vents, or an obviously oversized load, those issues can be addressed without specialized tools. However, if the Pr.9 parameter needs to be adjusted or the motor needs to be tested for faults, that work typically requires access to the inverter drive's programming interface and electrical diagnostic equipment, which are better handled by a qualified technician.

Resetting the unit may temporarily clear the displayed code, but because TH is based on a cumulative thermal value, the accumulation does not instantly reset to zero. If the underlying cause such as excessive load or an incorrect Pr.9 setting is not corrected, the thermal value will continue to climb and the pre-alarm will reappear. Address the root cause before relying on a reset.