HVAC Code Lookup

Ruud Furnace Code 22

Soft lockout

Main limit open. The temperature inside the heat exchanger area has climbed above a safe preset value, so the limit switch opened and gas heating is blocked until it cools. Almost always an airflow problem. If the limit stays open more than 150 seconds the control also shows 61 and can go to hard lockout.

Manual wording: “MAIN LIMIT OPEN ... The main limit has opened or is sensed to be opened. This normally means that the temperture inside the heat exchanger area has gone above a certain predetermined critical value and heating operation is not permitted until the limit cools to within normal parameters.”

Documented for: (-)97V, (-)96V; on (-)801S/(-)801P code 22 reads MAIN LIMIT OR HALC OPEN

Likely causes, most common first

  1. No airflow
  2. Insufficient airflow
  3. Faulty limit control
  4. Loose or faulty wiring
  5. Dead (non-functional) blower
  6. Input too high

What you can safely check yourself

  • Check the air filter and replace it if it is dirty - this is the number one cause.
  • Open all supply registers and clear anything blocking return air grilles.
  • Make sure the blower door is fully closed and seated.
  • Let the furnace cool, then power cycle once at the furnace switch.

When to call a technician

If the code comes back after a clean filter and open registers, the blower, ductwork static pressure, limit control or gas input needs a technician. Never jumper or bypass the limit switch.

A Ruud furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Other Ruud codes