how to troubleshoot my Toyota Highlander Third Generation (2014-2019) heating system

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the battery to ensure safety while working on electrical components.

2. Check Coolant Level

• Locate the coolant reservoir and ensure it is filled to the appropriate level.
• If low, add the recommended coolant type (Toyota Super Long Life Coolant).

3. Inspect and Bleed the Cooling System

• With the engine cool, remove the radiator cap.
• Start the engine and let it reach operating temperature.
• Monitor the temperature gauge and add coolant as necessary to keep the level full.
• If air bubbles are observed, continue to run the engine until no more bubbles escape.

4. Test Heater Control Valve

• Locate the heater control valve in the engine bay.
• Use a multimeter to check if the valve is receiving power when the heater is turned on.
• If it is not functioning, replace the heater control valve.

5. Inspect Heater Core

• Remove the dashboard panel as required for access to the heater core.
• Check for any visible signs of leakage or blockage in the heater core.
• Flush the heater core if blocked, or replace it if leaking.

6. Reassemble and Refill

• Once repairs are complete, reassemble any components removed.
• Refill the cooling system with the proper coolant mixture.
• Reconnect the battery.