Why does the car leak coolant when the air conditioning is turned on?
2 Answers
It is unlikely for a car to leak coolant when the air conditioning is turned on. Below is some information about car air conditioning issues: Lack of refrigerant or leaks: Most cases of insufficient cooling are due to a lack of refrigerant. You can first check the air conditioning pressure. If both high and low pressures are low, it generally indicates a lack of refrigerant, and adding refrigerant to the appropriate pressure level should resolve the issue. Excessive pressure in the air conditioning system: The car's air conditioning system operates under pressure due to the compressor. If too much refrigerant is added or there is a blockage in the pipes, the system pressure can become too high. In such cases, the control system will disengage the compressor's electromagnetic clutch to stop the compressor. The solution is simple: confirm the excessive pressure and release some refrigerant to restore normal pressure. Damaged evaporator temperature sensor or pressure switch: The evaporator, also known as the evaporator box, is located in the air duct under the dashboard. Here, the refrigerant vaporizes and absorbs heat to produce cold air. When the airflow passes through the small channels in the evaporator, it is cooled. The compressor stops when the temperature approaches freezing. If this sensor is damaged and frequently gives false readings of freezing temperatures, the compressor will stop frequently.
I've driven quite a few cars and find it quite common for coolant to leak when the AC is turned on. Mostly, it's because the AC operation kicks in the fan, increasing pressure on the cooling system and exposing existing weak points. For example, small cracks in the radiator or loose hose connections might be fine when the AC is off, but once the fan starts running with the AC on, the increased vibration can squeeze out the coolant. Additionally, higher engine temperatures can cause seals to age and fail more quickly. The AC compressor makes the engine work harder, raising temperatures and speeding up coolant circulation, which can reveal hidden issues. I recommend checking the radiator and hose connections as soon as possible—don't wait until the engine overheats and stalls. Regularly check under the car for any green or pink fluid drips; early repairs can save you a lot of money.
