Auto Air Conditioning & Heater Repair: 2004 Sienna ac problem - on then off then on again, amp fuse, magnetic clutch

Question
Hi,
My 04 Toyota Sienna AC first started blowing warm air after about 15 minutes of cold air, then failed to start all together. The ac clutch was replaced and had burned up. The new clutch then burned up a few days later. The magnetic clutch relay was replaced (as noted in a Toyota service bulletin) along with a 10 amp fuse and another new clutch. It now works great for about 10 minutes, then the compressor and fans shut off on their own- the green AC light remains on solid. If I leave it on, the fans and compressor eventually come on for a few seconds then shut off again. This cycle keeps repeating. If I shut the AC off and then turn it on again it may work fine and cold for another 10-15 minutes but eventually shuts down on its own again and keeps trying to restart. The dealer has looked at it but couldn't find anything. An auto electric shop found some pins in a pressure sensor that they thought were too far apart and set them right but this did not change anything. Any ideas? the frustation is building as you can imagine.
Thansk so much!
Steve

Answer
HI Steve

Try and get some pressures for me.  That is really the only way.  If your pressures are good for 10-15 minute and then they start to drop until the compressor stops.  Then you need to see if the system gets into a vacuum 0 or below if so then change your expansion valve and drier.  If it starts to drop, compressor stop, and pressures start to come up steadily and will not start.  Then check your thermostat.  Good luck let me know.