York TM9V080B12MP11 Error Code 5 Red Flashes: Limit Circuit Open Over 15 Minutes
What Does Code 5 Red Flashes Mean?
A 5 red flash code on the York TM9V080B12MP11 indicates the limit circuit has been continuously open for more than fifteen minutes. When the limit stays open this long, the control board interprets it as a manual-reset rollout switch having tripped rather than a routine overheating event. Rollout switches are positioned to detect flames escaping from the heat exchanger — when they trip, it often points to a cracked or failed primary heat exchanger or a combustion air problem.
The furnace has entered a hard lockout. It will not attempt to restart automatically. Even after the underlying cause is fixed, power must be cycled off and back on to reset the control board. The rollout switch itself has a manual reset button that must be pressed by a technician after the cause has been identified and corrected.
Contact a qualified HVAC technician immediately. This is a serious safety condition. A cracked heat exchanger can allow combustion gases, including carbon monoxide, to enter your home's ductwork. The technician must inspect the heat exchanger, verify combustion air supply, and check inducer motor operation.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Manual-reset rollout switch has tripped | Most common | ✗ Call a pro → |
| Primary heat exchanger failure or burner problem | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- Immediately — this code frequently indicates a heat exchanger problem with potential carbon monoxide risk
✓ Verified against manufacturer service manual — March 2026