Ruud Furnace Code F
Status
Continuous fan mode. The thermostat is asking for the blower to run continuously with no heating or cooling.
Manual wording: “CONTINUOUS FAN MODE ... This code is displayed anytime there is a call for continuous fan from the thermostat.”
Documented for: (-)97V, (-)96V, (-)801S/(-)801P
Likely causes, most common first
- Thermostat fan switch set to ON
What you can safely check yourself
- If you did not want the fan running all the time, set the thermostat fan switch from ON to AUTO.
When to call a technician
No action needed - this is a normal operating code.
A Ruud furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- Installation Instructions for Upflow Condensing Modulating, Communicating Gas Furnaces - (-)97V Series (92-24161-126-04) (Rheem Manufacturing Company (Ruud brand), U97V series modulating condensing gas furnace (and U98V); TABLE 18 normal operation codes, TABLE 19 fault codes, pages 94-104) · checked 2026-08-25
- Installation Instructions for 4 Position Condensing Two-Stage, Communicating Gas Furnaces - (-)96V Series (92-24161-124-08) (Rheem Manufacturing Company (Ruud brand), U96V series and (-)(-)96MDV two-stage condensing gas furnaces; TABLE 19 normal operation codes, TABLE 20 fault codes, pages 111-120) · checked 2026-08-25
- Installation Instructions for Downflow Single Stage Gas Furnaces - (-)801S / (-)801P Downflow Series (92-24161-143-03) (Rheem Manufacturing Company (Ruud brand), U801S, U801P, (-)(-)80DSS, (-)(-)80DSP 80% single-stage gas furnaces; DIAGNOSTICS AND FAULT CODES, page 34) · checked 2026-08-25