How to Fix / Troubleshooting

Safety: Turn off power before removing panels. Metal surfaces may be hot.

Steps to check:

Replace filter: Install a clean filter of the correct size and recommended MERV rating.
Open airflow paths: Open all registers and ensure returns are not blocked by furniture or drapes.
Check blower operation: Observe whether the Daikin blower starts promptly after ignition and runs at a strong airflow. Weak or delayed blower operation can cause overheating.
Inspect high-limit switch: The high-limit is usually mounted on the heat exchanger panel. If it has a manual reset button, press it once after the furnace cools. If it trips again, stop and call a technician.

Persistent high-limit trips indicate a design or mechanical airflow problem that should be evaluated by an HVAC professional.

Daikin furnace runs inducer and ignites but shuts down on high limit; unit may short-cycle with very hot supply air.

Possible Causes