3 flashes — Open High Limit

What does 3 flashes mean?

The diagnostic LED flashes three times, meaning the high limit switch has opened. This safety device trips to prevent the furnace from overheating.

• Overheating due to blocked air intake or exhaust
• Malfunctioning blower motor
• Faulty high limit switch
• Restricted airflow from vents

Click steps to track your progress.

1. 1

   Check that the furnace air intake and exhaust vents are clear of obstructions.

2. 2

   Ensure the blower motor is running and moving air.

3. 3

   Verify that all furnace vents inside the RV are open.

4. 4

   Do not operate the furnace if overheating is suspected; allow it to cool completely.