I have retro fitted from R12 to R134, installed new compressor witht he Right Pag oil, Sucked all the old R12 out and filled to the right amount of Freon in it. Ac blew cold for about 2-5 mins then i turned vehicle off. Came back around 30 mins later and now ac not blowing cold air out. I have noticed now that when the compressor kicks on the vehicle idles really low and wants and does shut off.

Any hints or advice on what could be the problem?

Could it be a switch problem? faulty compressor? etc.?