Furnace short cycles: starts, runs for a few minutes, then shuts off and restarts frequently.

Safety First: Turn off power before accessing internal components.

• Replace or clean filter: A clogged filter is the most common cause. Use the correct size and type recommended by Thermo Pride.
• Open all vents: Ensure all supply registers and return grilles are open and unobstructed.
• Check blower speed: If accessible and labeled, verify the heating speed tap on the blower motor is set according to the installation manual (advanced users only).
• Observe limit operation: If the burner shuts off but the blower continues for a while, the high limit may be opening. This requires a technician to confirm and possibly replace the limit or correct duct/airflow issues.