Rheem R801SA furnace code 22: Main limit or HALC open
Professional repair
What does code 22 mean on a Rheem R801SA (801S downflow) furnace display? Code 22 means the main limit or the HALC is open. The limit protects against excessive outlet air temperature, so the control stops burner operation while it is open.
Before you touch anything: the six signs that mean stop troubleshooting and call a pro →
Safe checks before calling
If the accessible filter is dirty, replace it with the same size, and never run without one. Confirm supply and return registers are open and unblocked.
If 22 returns after airflow checks, a technician measures temperature rise, blower performance and manifold pressure. Limit replacement must match OEM ratings exactly, and the limit must never be bypassed.
Possible causes
- Low airflow from a clogged filter or closed registers DIY-CHECKABLE
- Overfiring from excessive gas input or manifold pressure TECH
- Blower not moving enough air through the furnace TECH
Parts for this code
No model-verified part number is listed here. Have the fault diagnosed and the correct part matched to your furnace before ordering.
Questions about this code
What does code 22 mean on a Rheem R801SA (801S downflow) furnace display?
Code 22 means the main limit or the HALC is open. The limit protects against excessive outlet air temperature, so the control stops burner operation while it is open.
How do I fix Rheem R801SA furnace code 22?
Replace a dirty filter or open blocked registers first, then watch whether the code comes back. If it recurs, or appears with 61, stop there and book service rather than letting the furnace keep tripping.
How much does it cost to fix Rheem R801SA furnace code 22?
If a dirty filter caused the restriction, the filter may be the only expense. Other causes require airflow and gas-input testing before blower, duct or gas work is priced.
Related symptoms
These symptoms can appear alongside this code. The link is an association, not a diagnosis, and code meanings vary by brand, model and control.
Applies to
R801SA / 801S downflow single-stage 80% furnace with PSC motor
Different Rheem generations use different code maps. If your series isn't listed, don't assume this meaning — check your blower-door label.
Verified against Installation Instructions for Downflow Single Stage Gas Furnaces, p.34
Verified against Rheem 801S Series Installation Instructions — OEM143-14 mirror, p.34
Verified against Rheem 801S Series Installation Instructions — OEM143-14 mirror, p.43
Last verified 2026-10-07 · page updated 2026-10-07 · how we verify
Related Rheem furnace codes
These codes use the same rheem 801s downflow single-stage control (manual 92-24161-143-14) system.