The AC in my 99 Grand Cherokee just pumps out heat. It also runs pressures on the high side to 500 psi. Start it cold, turn on the AC and the pressure goes up.Within the past year both fans, compressor, orifice tube condensor have been replaced. Noticed that the clutch fan rotates ccw while the radiator fan rotates in the opposite direction, Doesn't make sense to me. Any ideas?

 

That head pressure is way too high, I'm surprised the safety valve on the compressor hasn't let loose. Sounds like you have a blockage someplace. Has sealer ever been introduced into the system?

 

Safety valve has blown off a couple of times. Sealer has never been introduced. Time to look for a new mechanic I guess.

 

The blockage could be almost anywhere. Usually if it is in a hose you will feel a noticeable temperature difference on either side of the choke point. It might also be the expansion valve is stuck closed, or a chunk of something is stuck stuck in the evaporator. (Maybe the previous owner used sealer? That's a common cause of this type of problem.)

Source of the blockage aside from hardened sealer could be internal delamination of a hose, busted open dessicant bag in the drier, or shrapnel from the compressor. (The latter is unlikely as your compressor obviously works and it would be making some pretty bad noises if it were coming apart internally.)

Most likely the system will need to be taken apart and components inspected.