Why is the car air conditioner blowing hot air?
2 Answers
The reasons why the car air conditioner blows hot air when set to cold are as follows: 1. Refrigerant deficiency: The principle of air conditioning cooling is that the refrigerant evaporates and absorbs heat from the air, thereby causing the blower to output cold air. Therefore, if there is insufficient refrigerant in the air conditioning system, the cooling effect will definitely be poor. When the air conditioning cooling is poor, the first step should be to check the refrigerant pressure. If both the high and low pressure readings are below standard, it is likely due to a refrigerant deficiency. 2. Air conditioning compressor failure: The role of the air conditioning compressor is to pressurize the refrigerant. After the refrigerant is cooled by the condenser, it further liquefies and is eventually delivered to the evaporator box to vaporize and absorb heat. If the compressor fails, it will result in low liquefaction of the refrigerant, preventing it from fully vaporizing in the evaporator box and making it difficult to provide effective heat absorption.
I ran into this issue myself not long ago—suddenly getting blasted with hot air from the AC was super uncomfortable. The cause might be pretty simple, like forgetting to turn the temperature knob to cooling mode. In summer, many people turn on the AC as soon as they get in the car but forget to switch modes, so naturally, the air blows hot. Another possibility is that the compressor isn’t kicking on. If you hear the engine running but no cold air comes out, it’s likely the compressor is stuck or there’s insufficient refrigerant—older cars tend to leak refrigerant and need refills. A fan issue could also cause only hot air from the engine side to blow through, so you’d need to check the blower motor or fuses. My advice: first check the settings and fiddle with the temperature knob. If that doesn’t work, head to a repair shop ASAP to avoid heatstroke on the road. Regular maintenance of the AC system, like cleaning filters and topping up refrigerant, can prevent these headaches.
