i have a 2000 dodge ram 2500. the ac works when i start the truck then about 10 to 20 mins after dribing the ac does not blow cold. i know for sure its charged. i changed the cycling switch but that does not seem to have fixed it. any ideas? maybe the pressure switch? i have no idea. any suggestions would be great

 

my A/C line pressure changes significantly between a cold start and a warmed up truck. Check pressure at both times and report back (use a manifold gauge set, not just a low side checker gauge). Watch the compressor clutch too to see if it starts cycling after the truck as warmed up, which indicates low refrigerant.

Also, check your pressure after you turn off the truck to see how quickly it levels off. If it takes too long, (more than 30 sec) you're orifice tube is clogged. If all that checks out, you might have a bad evap core.