Why Does the Car Air Conditioner Blow Hot Air?
2 Answers
The reasons why a car air conditioner blows hot air are as follows: 1. The controller signal may not be transmitted to the HVAC assembly, requiring inspection of the wiring from the controller to the HVAC unit; 2. The controller signal fails to transmit, indicating an issue with the controller itself; 3. A problem with the blend door servo motor on the HVAC assembly, where it does not actuate upon receiving the controller signal; 4. Deformation of the blend door or detachment of the sealing strip on the HVAC assembly, resulting in loss of effective sealing; 5. Cleaning the radiator and condenser. The radiator and condenser are vital components of the vehicle's cooling system and air conditioning. Over prolonged use, dust, mud, and catkins can accumulate in the gaps between them, affecting water temperature and air conditioning cooling performance; 6. Checking the air conditioning pressure and replacing the refrigerant. First, inspect the (H) high-pressure detection pipe and (L) low-pressure detection pipe, connecting them to the refrigerant pressure gauge. After connecting the gauge, start the vehicle and let it idle. Turn on the air conditioning switch and set the system to maximum for operation testing. During idle, the high pressure should not exceed 300, and the low pressure should not exceed 60. After idling for several minutes, increase the engine speed by pressing the accelerator to observe pressure gauge changes and check if the air conditioning compressor is functioning normally.
I just encountered the issue of the A/C blowing hot air last week, and later found out it was due to a lack of Freon in the system. For a car's air conditioning to cool, refrigerant needs to circulate within the system. If there's a crack in the piping or loose connections causing a leak, insufficient refrigerant will prevent the compressor from functioning properly. Another possibility is that the condenser fins are clogged with mud or leaves, reducing heat dissipation and lowering cooling efficiency. Also, remember to check if the A/C switch is engaged—sometimes accidentally adjusting the knob to the outside air circulation mode can let hot air directly enter the cabin. These situations can all cause the A/C to blow hot air. It's recommended to visit a repair shop as soon as possible to check the refrigerant pressure with a gauge and clean the condenser surface.
