Status LED flashes green four times repeatedly; blower may run continuously; furnace does not heat.

Safety first: Turn off power before removing blower or coil access panels.

Steps to check:

• Inspect return air path: Ensure return grilles are not blocked and that the return duct is intact and not collapsed.
• Check evaporator coil (if AC installed): Remove the coil access panel above the furnace. Inspect the underside of the coil for heavy dust or biological growth. A severely clogged coil must be cleaned by a technician.
• Locate auxiliary limits: Some Coleman furnaces have additional limit switches on the blower deck or near the coil. Check for continuity and replace any that remain open after cooling.
• Verify blower speed tap: On PSC motor models, ensure the correct speed tap is connected to HEAT on the control board. Too low a speed can cause overheating.

If limits continue to open, have an HVAC professional evaluate duct sizing, blower performance, and coil cleanliness.