HVAC Code Lookup

York Furnace 11 Red Flashes

Hard lockoutShown as: Eleven red flashes, then a two-second pause, repeating

The main limit switch opened and stayed open for more than five minutes, which the control reads as a failed blower. It enters a hard lockout that only a power cycle clears.

Manual wording: “11 RED FLASHES: This indicates that the main limit switch has opened its normally-closed contacts and has remained open for more than five minutes. This condition is usually caused by a failed blower motor or blower wheel. The control will enter a hard lockout...”

Documented for: TG8S, TG9S, TM9E, TM9X, TM8X, TM9T, TM8T, TM9V, TM8Y, TM9Y

Likely causes, most common first

  1. Failed blower motor
  2. Failed or seized blower wheel

What you can safely check yourself

  • Check and replace the air filter
  • Open blocked supply registers and clear anything covering the return grille
  • Turn the furnace off at the service switch for a minute and back on once after the airflow problem is fixed

When to call a technician

A blower motor or wheel failure is a technician replacement job. If the code returns after one reset, stop resetting it and call for service.

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

Sources

Other York codes