Rheem R801SA furnace code C: Compressor running
Info — not a fault
What does C mean on a Rheem R801SA (801S downflow) furnace display? C means the compressor is running for cooling or heat-pump heating. It is a normal operating display on this control, not a fault.
Safe checks before calling
If you expected gas heat, check whether the thermostat is set for cooling or heat-pump operation.
Questions about this code
What does C mean on a Rheem R801SA (801S downflow) furnace display?
C means the compressor is running for cooling or heat-pump heating. It is a normal operating display on this control, not a fault.
Does Rheem R801SA furnace code C mean I need a repair?
C needs no repair. If the house is not reaching temperature while C shows, a technician should look at the cooling or heat-pump equipment and thermostat setup rather than the furnace burner.
How much does it cost to fix Rheem R801SA furnace code C?
C is a normal display and implies no repair bill. Any cost would come from separately diagnosing the cooling or heat-pump system if it underperforms.
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 Rheem 801S Series Installation Instructions — OEM143-14 mirror, p.34
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.
| Pattern | Meaning |
|---|---|
| 0Single-digit display: 0 | Standby |
| HSingle-character display: H | Gas heat on |
| 93Two-digit display: 93 | Internal control fault |
| FSingle-character display: F | Continuous fan |