A/c starts off cold

My 04 Chevy suburban blows cold for about 15 minutes then turns hot…sometimes it will turn back cold, but not lately

I had a similar problem with a Ford Aerostar. It turned out to be the fan clutch. The technician figured it out by hooking up the gauges and running the air conditioning on the gauges. The reading was way too high. He then brought his shop fan around to the front of the van and turned it on. The air flow cooled the condenser, the pressure reading dropped on the gauges and the air conditioning started blowing cold air. The fan turned, but not fast enough with the defective clutch for proper air flow through the condenser. The engine, however, didn’t overheat.

I’ve got a similar problem, but it is due a missing fan shroud. Because of an accident, the fan shroud shattered and the remnants had to be removed. Without the shroud, the fan isn’t pulling as much air through the condenser coil to keep the A/C cool while idling more than a few minutes. However, the truck doesn’t overheat.