I have 2005 Dodge Ram 3500 5.9L Turbo Diesel 6-speed manual transmission. While I was driving the A/C was working fine and blowing cold air, when I stopped (the engine was still running) it started blowing hot air just for about ten second and then it was fine again. I went to mechanic to measure the Freon pressure. Initially, the pressure was low: 32 and high: 250-300, about five seconds later, the high pressure went to 500 and ten seconds later it was back to normal. Any help is appreciated. Thank you.

 

remove the condensor and the intercooler and clean the radiator fin with a water hose. Probably a bunch of crap stuck in the fins. I've seen this a number of time.