Why is the air conditioner not blowing hot air?
2 Answers
Car air conditioning heating system not producing heat can be attributed to two main reasons: one is caused by abnormalities in the engine cooling system, and the other is due to poor operation of the heating control mechanism. Below is relevant information regarding these two aspects: Possible issues with the cooling system: 1. The thermostat is constantly open or opens too early, causing the cooling system to prematurely enter a large circulation cycle. With low external temperatures, the cold air quickly cools the antifreeze, resulting in low engine water temperature and insufficient heating. 2. Damage or slippage of the water pump impeller reduces the flow rate through the small heating radiator, leading to insufficient heat. 3. Air pockets in the engine cooling system hinder proper circulation, causing high water temperature and inadequate heating. If air pockets persist in the cooling system, it may indicate a damaged cylinder head gasket allowing air into the cooling system. If the inlet pipe of the small heating radiator is hot while the outlet pipe is cold, this suggests a blockage in the small heating radiator, which should be replaced. Issues with the airflow control mechanism: 1. The car's heating system uses a blower to direct heat from the small heating radiator into the cabin. If the airflow is insufficient or the distribution between hot and cold air is poor, the heat from the small heating radiator cannot be effectively dispersed, resulting in low heating temperature. In this case, first check if the air filter is dirty or clogged, clean it, and replace it if necessary. 2. Inspect the operation of the blower at each speed setting to ensure sufficient rotation speed at every level. If the knob is adjusted to the heating position, the airflow is strong, and the direction is normal, but cold air is still blowing, check if the control cable for the heating box's hot/cold air flap is detached, if the heating impeller is damaged, or if the flap is dislodged. After troubleshooting these issues, the heating should function properly.
I've encountered quite a few situations where the car AC fails to blow hot air during my years of driving. Usually, these common culprits are to blame: Insufficient or leaking coolant is the most frequent offender, preventing the heater core from warming up properly; a stuck or misaligned blend door causes failure in mixing hot and cold air; a faulty thermostat means the engine can't reach optimal temperature to produce heat; if the blower fan operates slowly or stops working, hot air naturally won't circulate; there might also be clogged ducts or malfunctioning temperature control modules. I remember last winter when my AC suddenly failed during a business trip - not only was I shivering from cold, but the fogged-up windows nearly caused an accident! The repair shop later traced it to coolant leakage. Regular checks of coolant levels and fan settings are crucial - don't wait until problems escalate, which wastes money and poses risks. At the first sign of abnormality, prioritize safety by conducting immediate troubleshooting.
