Dodge: passenger side a/c warm, vacuum problem, check valve

Question
my 2004 ram 1500 blows cold on drivers side but warm on passenger side. sometimes its fine and then warm/hot air starts blowing out of passenger side.
any answers? thanks

Answer
If you have cold air on the drivers side,then it has to be that the flapper lid in the dash is not closing all the way.If it was the compressor or condensor you'd be feeling the same temp on both sides.On the 1500 you sometimes have to add a check valve on the line that runs through the firewall on the passenger side to the back of the temp selector.It is a vacuum problem.Have you ever noticed that while driving the vents change from the dash to defrost?