Panasonic Air Conditioner Error Code H24

H24 indicates that indoor heat exchanger temperature sensor 2 has been detected in an open or short circuit condition continuously for 5 seconds. The sensor monitors coil temperature inside the indoor unit, and the control board halts normal operation when it cannot obtain a valid reading from this sensor. The fault can stem from a disconnected connector, a broken wire, or a failed sensor element.

The system will typically prevent normal operation when H24 is active, as the control board cannot properly regulate the heat exchanger without valid temperature data from sensor 2. Attempting to bypass or ignore this fault could result in coil freeze-up or overheating conditions. It is best to stop using the unit and resolve the fault before resuming operation.

A power reset may temporarily clear the H24 code, but the fault will return if the underlying problem with sensor 2 or its wiring has not been corrected. Because the error is triggered after the fault condition persists for 5 seconds continuously, any reset is only a short-term measure. The sensor, wiring, and connector must be inspected and repaired or replaced to permanently resolve the error.

Start by inspecting the sensor 2 lead wire and connector for any visible damage, loose connections, or corrosion. If the wiring looks intact, use a multimeter to measure the resistance across the sensor terminals and compare the reading to the expected resistance at the current temperature. If the sensor reads open or shorted, it will need to be replaced. If the sensor tests correctly, the wiring harness or control board may require further evaluation by a technician.

If the issue is simply a loose or corroded connector, repair costs may only involve a service call fee, which typically ranges from $75 to $150. If the sensor itself needs replacement, parts and labor combined generally range from $100 to $300 depending on the specific model and local labor rates. A control board replacement, if required, would be significantly more expensive.