What Causes a Car Air Conditioner Not to Cool When the Pressure is Normal?
3 Answers
When the air outlet is functioning normally and the compressor is working properly, the reasons why a car air conditioner fails to cool are as follows: 1. Lack of refrigerant: Car air conditioners typically require refrigerant replenishment every 2-3 years, with some vehicles needing it annually. Even if the air conditioning system is tightly sealed, refrigerant can still escape, especially if there are minor leaks in the air conditioning pipes or condenser. 2. Damaged air conditioning flap: The failure of the air conditioning flap motor is relatively rare but not unheard of. A malfunctioning flap motor is troublesome as it is usually located in the lower middle part of the dashboard, serving as the main switch for the air vents. If it fails, the switch is effectively broken, and even if the air conditioner can produce cold air, it can only escape through gaps, akin to quenching thirst with poison. 3. Dirty condenser: During summer, poor air conditioning performance is often noticed. When the air conditioning system is tested and found to be functioning normally with standard high and low pressures, car repair shops often recommend cleaning the radiator. The primary purpose of cleaning the radiator and condenser is to improve heat dissipation. Accumulation of springtime poplar and willow catkins on the condenser can lead to issues like excessively high engine temperatures or poor air conditioning performance.
I've been repairing cars for nearly twenty years and have encountered many cases where the air conditioning doesn't cool despite normal pressure. The most common issue is a faulty AC compressor, where either the clutch coil or internal pistons are worn out, preventing refrigerant compression. A stuck expansion valve can also block refrigerant flow to the evaporator. Another hidden problem is the blend door in the air ducts getting stuck in the heat position, blocking cold air. A malfunctioning electronic control module can also cause system misjudgment. These all require professional equipment for diagnosis. I recommend stopping AC use immediately to avoid damaging more components.
Last time my car had this issue, it was blowing hot air even though the pressure was normal. The mechanic found that the evaporator temperature sensor was faulty, causing the computer to misjudge the temperature. Another time, my colleague's car had insufficient cooling due to a faulty fan speed controller. Additionally, if there's a blockage in the AC lines, especially if it's frozen near the dryer, the pressure gauge might show normal but the cooling effect disappears completely. You shouldn't delay fixing this—it's unbearable driving in the summer like that.
