What It Means
Main limit switch open due to furnace high-temperature limit trip.
Rheem Furnace
Rheem Furnace Error Code 22
Troubleshooting guide for the Rheem Furnace system fault 22.
Possible Causes
- Restricted airflow or dirty filter.
- Blocked return or supply vents.
- Dirty evaporator coil or undersized ductwork.
- Failed blower motor or improper speed setting.
Not sure which one it is — or if it's none of these? Try ACLogics today.
Disclaimer: This information is for general reference. Error codes can vary by model and production year. Always refer to your machine's specific manual and the information printed on the unit itself.
New to this code? Click to see why this happens
Full Diagnosis
Main limit switch open; furnace overheating/high-limit condition.
All Recorded Causes
Restricted airflow, dirty filter, blocked return or supply vents, dirty evaporator coil, undersized ductwork, failed or slow blower, or incorrect blower speed/airflow setup.
Verify Before Replacing Parts
- Confirm the exact Rheem model family and furnaces context before acting on a generic code description.
- Confirm filter condition, blower operation, and coil cleanliness before replacing any controls — start by ruling out whether restricted airflow, dirty filter, blocked return or supply vents, dirty evaporator coil, u….
- Measure airflow-related readings that match the symptom, such as temperature split or static pressure, and check whether the next candidate on the list.
- After the correction, run the system long enough to confirm the furnaces fault does not return under normal load.
Still unsure about this fault?
ACLogics walks you through Rheem Furnace diagnostics step-by-step — so you confirm the cause before swapping parts.
