York TM9T100C16MP11 Error Code 11 Red Flashes: Limit Circuit Open 5-15 Minutes
What Does Code 11 Red Flashes Mean?
An 11 red flash code on the York TM9T100C16MP11 means the limit circuit has remained open for more than five minutes but less than fifteen minutes. The control board interprets this duration as a likely blower failure rather than a simple airflow restriction. Without the blower moving air across the heat exchanger, the furnace cannot cool itself and the limit switch stays tripped.
A failed blower motor is the most common cause. The motor may have burned out, seized, or lost a winding, preventing it from spinning at all or spinning fast enough to move adequate air. A failed or damaged blower wheel — the fan blade assembly attached to the motor shaft — can also cause this condition if it has cracked, come loose from the shaft, or become clogged with debris.
The furnace has entered a hard lockout and will not restart until the problem is fixed and power is cycled off and back on. A qualified HVAC technician must inspect the blower motor and wheel, test the motor electrically, and replace any failed components.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Failed blower motor | Most common | ✗ Call a pro → |
| Failed blower wheel | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- When this code appears — blower motor or wheel failure requires professional diagnosis and replacement
Sources
✓ Verified against manufacturer service manual — March 2026