A/C blowing less cold air after a while


I’m driving a 2007 Audi A4. Today was a very hot day (95F), and driving on the freeway. The A/C starts off very cold, then after about 45 minutes it starts to blow significantly less cool air. Drove again a few hours later, and this happened again - very cold at first, and then significantly less cool after while. This has happened some in the past, but only on very hot days. Any thoughts about problems and solutions? Compressor? Or a leak? Will adding coolent alone do anything?

The evaporator coil may be icing up. Turn the air conditioning off for five minutes or so and then turn it back on and see if the air is cooled.


The icing up may be caused by a low refrigerant.