Panasonic Air Conditioner Error Code H23

H23 indicates an abnormality in the indoor heat exchanger temperature sensor circuit. The control board has detected either an open circuit or a short circuit on the sensor continuously for 5 seconds, causing the unit to shut down. The sensor is a thermistor mounted on the indoor coil that provides temperature feedback to the system. Diagnosis starts by checking the sensor connector at the indoor PCB and measuring resistance.

The unit will typically not operate normally while the H23 fault is active, as the system shuts down to protect itself. You should not attempt to bypass the fault and run the system without a functioning heat exchanger sensor, since that sensor is used to prevent coil freeze-up and control refrigerant flow. Address the fault before resuming normal use.

Repair costs vary depending on the root cause. If only a loose connector needs reseating, a service call fee in the range of $75 to $150 may be the only cost. Replacing a failed thermistor sensor typically adds $50 to $150 in parts plus labor. If the indoor PCB is at fault, board replacement can bring the total repair cost to $300 or more depending on the model and labor rates in your area.

A homeowner can safely check that the sensor connector is fully plugged in at the indoor PCB, which sometimes resolves the fault. However, testing thermistor resistance with a multimeter and replacing a failed sensor or damaged wiring requires comfort with electrical diagnostics and disassembly of the indoor unit. If you are not familiar with these tasks, a qualified technician should perform the repair.

A power reset may temporarily clear the H23 code if the connector was intermittently loose, but the fault will return if the underlying cause is not corrected. Because the error requires a continuous 5-second fault condition to trigger, a reset alone is not a repair. The sensor, wiring, and connector must be inspected and tested to prevent the code from reappearing.