Kip,
It sounds like the A/C guy you talked to is on a profit sharing plan. Unless you have metal junk flowing around in the system from a previous compressor that grenaded, there is no reason a compressor should fail as long as you have a sufficient charge and the proper oil. R134 is not compatible with mineral oil used with R12 so you have to replace some or all of the oil. The oil of choice for a conversion is Ester oil, because it is tolerated by any mineral oil left in the system. You mentioned extra heat. The recommended 134 charge is 80% of R12, because R134 head pressures can be 20 to 100 lbs more than R12. Actually a company called EF Products, Inc. makes a product that consists of a set of fittings and two plastic tubes filled with liquid. you screw the tubes onto the R12 service ports, and with a socket wrench you turn the fitting on the end of the tube until all the liquid is forced into the system. Then you just charge the system with R134. The fluid in the tubes makes the mineral oil compatible with R134. The reason for oil in an A/C system is circulate with the refrigerent to lubricate the compressor. Interestingly enough this coversion kit is manufactured in Dallas, Texas.

Peter

__________________
Auto Zentral Ltd.