2001 Chevy Silverado A/C?

[David]

I just got a 2001 Chevy Silverado the other day. it has a 5.3 v8 with 102,xxx miles on it.

the problem with is with the A/C. it cools great. but after about 20 min of driving on the highway it starts to blow less cool and less air comes out of the vents. also a dust, smoke type stuff comes out of the vents,

i got it looked at and the chevy dealership put in freon and did some other work to it and said it was fine but it keep doing the same thing. could it be the compressor or a dirty air filter?

any help is apreciated

Thanks

 

[don r]

Have the ac ducts checked to make sure the cool air isn't being mixed with air from outside or the heater core. There may be a cracked or loose vacuum control hose.

 

[ironbutt]

the evaporator is freezing up. the ice buildup reduces the flow of air from the vents. The smoke you see is the vapor coming off of the ice, just as when you open the freezer door and a fog rolls out. have the freon level checked again. It may be under or overcharged