Rheem Furnace Troubleshooting

When the colder seasons are approaching, it is necessary to make sure that your home heating system is in the best possible condition. Wintertime furnace breakdowns are far more than just an inconvenience; they pose serious health and safety risks.

If you own a Rheem furnace and are having problems, this article should help you figure out what’s wrong and how to fix it, or at least know when to call a pro.

Troubleshooting the Most Common Issues in Rheem Furnaces

Check the Thermostat: Make sure the temperature is correct and the device is in "heat" mode. If it runs on batteries, you'll need to get new ones.

Inspect the Circuit Breaker: Check for a blown fuse or a breaker that has tripped. To see whether the furnace turns on again, reset the breaker or change the fuse.

Check the Gas Supply: Make sure the gas valve is open and look for any breaks in the gas supply. Turn off the main gas valve and contact an expert immediately if you detect gas.

Air Filter: A blocked air filter can limit airflow and cause short cycling, so be sure to check it for dirt and replace it if needed.

Thermostat Location and Calibration: To avoid inaccurate readings, place the thermostat away from any heat sources and out of direct sunlight. Adjust the course if that is feasible.

Inspect the Heat Exchanger for Overheating: Overheating, caused by a lack of ventilation or other technical problems, will cause the furnace to turn off. Look for clogged vents and make sure the blower motor is in good working order.

Check the Blower Motor: Ensure that it receives power and operates correctly. If not, the motor might need to be replaced.

Air Duct Inspection: Inspect the ductwork for any holes, cracks, or other obstructions that can reduce airflow. All vents must be open.

Blower Belt: If the blower in your furnace is operated by a belt, you should inspect it for signs of wear and tear and replace it if required.

Tighten Loose Components: Rattling sounds can be caused by loose screws or panels. Tighten any loose elements you find.

Lubricate the Blower Motor: If the noise is a screech, the blower motor or its belt might need lubrication or replacement.

Inspect the Burners: A banging noise upon startup could be due to delayed ignition. Clean the burners to ensure proper gas flow.

Relight the Pilot: Follow the manufacturer's instructions to safely relight the pilot. If the pilot light does not stay lit, the thermocouple may need to be replaced.

Check the Gas Valve: Ensure it is functioning properly and providing gas to the pilot light.

Inspect for Drafts: Ensure no drafts are blowing the pilot light out. Adjust the furnace or its components like its gas line to shield the pilot light from drafts.

Airflow Check: Ensure nothing is blocking air intake or exhaust. Check internal filters and external vents.

Inspect Safety Switches: Overheating can trigger safety switches that shut down the furnace. These may need to be reset by a professional if they continue to trip.

Inspect the Condensate Line: Make sure the condensate drain pipe is clear by inspecting it. Locate any line damage, such as cracks or holes, and fix or get it replaced as necessary.

Check the Condensate Pump: The condensate pump should be checked to make sure it is working properly and not getting clogged if it is installed.

Comprehensive Error Code Guide for Rheem Furnaces

It is important to know the error codes for your Rheem furnace to fix problems quickly. However, keep in mind that these codes are different from those for your Rheem water heater or air conditioner. Here are a few of the most common Rheem furnace error codes, what they mean, and how to fix them:

Error Code 0: Standby Mode

  • Explanation: The furnace remains in a ready state, awaiting a command to activate heating.

  • Action Needed: No intervention is necessary unless the system fails to activate upon demand.

Error Code F: Continuous Fan Operation

  • Explanation: The fan operates continuously without the heating cycle.

  • Action Needed: Adjust the thermostat settings from “on” to “auto” to correct this.

Error Code H: Active Heating

  • Explanation: The furnace is in the process of heating the home.

  • Action Needed: No action is required unless the furnace is operating when it should not be.

Error Code 10: One Hour Lockout

  • Explanation: After several unsuccessful ignition attempts, the furnace will lock out for one hour.

  • Action Needed: Inspect and troubleshoot components like the gas supply, igniter, and flame sensor. Reset the system to clear the lockout.

Error Code 11: Ignition Failure

  • Explanation: The system attempted to ignite but was unsuccessful.

  • Action Needed: Ensure proper gas flow, that the igniter is operational, and that the gas valve is functioning correctly.

Error Code 12: Weak Flame Detection

  • Explanation: The flame sensor detected a flame, but it is weaker than normal.

  • Action Needed: Clean or replace the flame sensor and ensure the burner is clear of debris.

Error Code 13: Flame Extinguished

  • Explanation: Initially detected, the flame was unexpectedly lost.

  • Action Needed: Verify operations of the gas supply, flame sensor, and draft inducer.

Error Code 14: Flame Detected Unexpectedly

  • Explanation: A flame has been detected inappropriately.

  • Action Needed: This could indicate a serious issue like a faulty gas valve or control board, requiring immediate attention.

Error Code 20: Twinning Fault

  • Explanation: Issues detected with the setup or wiring in systems configured in twin setups.

  • Action Needed: Verify the correct settings and wiring for twin configurations, ensuring compatibility of control boards.


Error Code 22: High Limit Switch Activation

  • Explanation: This switch activates due to excessive temperatures.

  • Action Needed: Check for airflow restrictions like dirty filters or blocked vents and consider replacing the switch if it is defective.

Error Code 26: Incorrect Electrical Wiring

  • Explanation: The electrical wiring setup is reversed, posing a safety risk.

  • Action Needed: Power down the system immediately and correct the wiring arrangement.

Error Code 33: Roll-Out Switch Tripped

  • Explanation: Indicates potential flame rollout or excessive heat outside the combustion area.

  • Action Needed: Inspect for blockages, ensure proper operation of the burner, and reset or replace the switch.

Error Codes 55 & 57: Issues with Pressure Switch

  • Explanation: The switch does not close (55) or open (57) as expected.

  • Action Needed: Examine the venting and intake, check the inducer motor, and inspect the pressure switch tubing.

Error Codes 58 & 59: Excess Water Detection

  • Explanation: Sensors detect too much water, likely from condensation.

  • Action Needed: Ensure the condensate drain is clear and that the drain pan is properly draining without overflow or hot water leak.

Error Code 61: Blower Malfunction

  • Explanation: The blower motor has encountered a fault and cannot operate.

  • Action Needed: Check for any damage or failure in the blower motor and capacitor, and verify electrical connections to ensure proper air supply.

Error Code 93: General Control Fault

  • Explanation: A general fault within the control board.

  • Action Needed: Typically, this requires a replacement of the control board by a certified professional.

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Furnace Troubleshooting Guides

Our comprehensive troubleshooting guide offers step-by-step solutions to common issues. From heating failures to airflow problems, we've got you covered."

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Choosing the Right HVAC Company for Rheem Furnace Troubleshooting: Comfort Union

When looking for a reliable and skilled HVAC technician, companies like Comfort Union should be at the top of your list. The certified technicians who work for our company are what set us apart and ensure that customers always get high-quality service.

Comfort Union is well-known for efficiently and quickly responding to both routine and emergency service calls while maintaining strict safety standards for your HVAC systems and their parts like gas piping, evaporator coil ductwork, and more. If you want your heating system problems fixed in a way that won’t put you, your family, or your house in danger, hiring a reputable service is your best bet.

Wish to know more about our services for your furnaces and water heaters? Contact us today and forget any trouble that comes your way!

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