Rheem HVAC Error Code 24: How to Fix It

Q: What does error code 24 mean on a Rheem HVAC system?

Error code 24 on a Rheem HVAC system indicates a return air temperature sensor fault. The control board is not receiving a valid signal from the sensor that monitors the temperature of air returning to the unit. This could be caused by a failed sensor, a loose wire connection, or a damaged control board.

Q: Can I keep running my Rheem HVAC with error code 24?

It is not recommended to continue running your system with error code 24 active. Without accurate return air temperature data, your HVAC cannot regulate itself properly, which can lead to inefficient operation, short-cycling, or potential damage to the compressor or heat exchanger. Address the fault as soon as possible.

Q: How do I reset a Rheem HVAC after fixing error code 24?

After repairing the return sensor fault, many Rheem units will clear error code 24 automatically when power is restored. If the code persists, try turning the system off at the thermostat, switching the breaker off for 30 seconds, then restoring power. Some models have a dedicated reset button on the control board — hold it for 3–5 seconds. Refer to your specific model's owner manual for exact reset instructions.

Q: How much does it cost to fix a Rheem HVAC return sensor fault?

If you DIY the repair, a replacement return air temperature sensor typically costs between $10 and $40 depending on your Rheem model. If you hire a professional HVAC technician, expect to pay between $75 and $200 for a service call plus parts, depending on your location and labor rates. If the control board also needs replacement, costs can rise to $300–$600 or more.

Q: Where is the return air temperature sensor located on a Rheem HVAC?

The return air temperature sensor on a Rheem HVAC is typically a small thermistor probe located in the return air duct near the air handler intake, or mounted on the evaporator coil housing inside the air handler cabinet. The exact location varies by model — check the wiring diagram printed on the inside of your unit's access panel or in the service manual for your specific model.

Abstract

Rheem HVAC error code 24 indicates a return air temperature sensor fault, meaning the control board is receiving an abnormal signal — or no signal at all — from the sensor that monitors the temperature of air returning to your system. This can cause your HVAC system to run inefficiently, short-cycle, or shut down entirely to protect itself. In most cases, the fix involves inspecting the sensor, its wiring, or replacing the sensor itself.