Dodge Repair: AC not cooling at low rpm, refrigerant pressure, 2005 dodge 1500

Question
I have a 2005 Dodge 1500, 4x4, 4.7 V8. went on vacation and on the way back the ac stopped cooling and was sending hot air into the cab. If I was driving at least 30mph it seemed to work fine. Every time I had to stop it started with the hot air. Any idea's?

Thank you,
Willie

Answer
Hi Willie,
Two possibilities: possibly the drive belt is slipping because it is too loose when you are at low rpm. So open the hood and press on the belt midway between two pulley to observe if you can depress it more that 1/2". If the belt seems tight enough then start the engine and have a helper rev the engine while you look to see if there is a good rotational speed relationship between the pulley on the compressor and the engine rpm (e.g. no apparent slipping). If that seems to be alright, then I suspect that you are at the lower limit on acceptable refrigerant pressure/content in the system so you would need to add some to the system. The clutch will only connect the compressor when the pressure in the system is sufficient.
Please see the PS below.
Thanks,
Roland