My air conditioning is not working properly. When I start the car it works fine for 20 minutes, then warm air will come out instead of cool air.
Allow the car to cool and restart will solve the problem but it will appears again after 20- 30 minutes.
No changes in coolant level is spotted, the car shows no sign of overheating. Speed of the car, road condition and ambient temperature seems doesn't have any effect on the problem.
Could anyone shed some light on this problem?