Ruud Furnace Code 67
Warning
Mid pressure switch open when it should be closed. Same modulating-only switch as code 65. The furnace keeps heating but firing rates between 50% and 65% are fixed at 70%.
Manual wording: “MID PRESSURE SWITCH OPEN, SHOULD BE CLOSED ... This fault indicates that the mid pressure switch is electrically open when it should be closed.”
Documented for: (-)97V modulating furnaces only
Likely causes, most common first
- Wind gusts
- Improper venting
- Bad wiring to mid pressure switch
- Bad mid pressure switch
- Bad furnace control
What you can safely check yourself
- Check the outdoor intake and exhaust terminations for snow, ice or debris.
- The manual notes wind gusts can trip it - if it clears when the wind drops, mention that to your technician.
When to call a technician
Vent length and construction, pressure switch and control replacement are technician work.
A Ruud furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- 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