2001 Yukon A/C Problem

My air works fine when the car is in motion and the RPM's are around 1.5 but when I stop at a red light the air coming out of the vents is no longer cold. When I start up again the air gets cool and continues until the next stop. Any ideas of what might cause this and how I might fix it?

The condenser needs air flow for the ac to work properly. At a light, the engine fan does this job. When you are driving, air will flow thur the condenser. The fan clutch could be bad and not providing enough air flow or the condenser fins are clogged.

First thing is to check the fan clutch and fins. If those are good, the ac system should be checked for proper operation.

//2000CAYukon

Mine does the same thing, but doesnt go to outside temps when at idle still blows cool. It is significantly cooler while driving. Ive powerwashed the radiator/condenser last year and didnt make a whole lot of difference and i know the fan is working properly.
Most cars ive had did this.

Mine does the same thing, but doesnt go to outside temps when at idle still blows cool. It is significantly cooler while driving. Ive powerwashed the radiator/condenser last year and didnt make a whole lot of difference and i know the fan is working properly.
Most cars ive had did this.

I am have the same issue in my 05 Denali. If I turn on the heat/ac, the only time is comes out the vents is if I am driving. If I am sitting at a light you can barely feel anything at all. Regardless of what fan setting I have it on, the faster I drive, the hard it blows and vice versa. Anyone have a suggestion as to the cause??? Any info would be greatly appreciated.