1. The cooling system is blocked: even if the heating box has been cleaned, some parts of the cooling system are still blocked, resulting in poor coolant flow and affecting the heating effect. You can check and clean the entire cooling system, including the water pump, radiator and other components, to ensure the smooth flow of coolant.
2. Air-conditioning control panel failure: Air-conditioning control panel failure, resulting in inaccurate temperature adjustment or heater system can not work normally. Use the fault diagnosis tool to check whether the air conditioning control panel is faulty, and replace the control panel if necessary.