I have a 1989 b2200 in the shop. came in originally for an intermittent a/c clutch problem. found the pressure switch to be bad replaced it and the compressor was bad as well so we replaced that also, i have now put 2 other compressors on a new drier, new evaporator core, and expansion valve on it and once the system is charged and the clutch is engaged the low side pulls vacuum instead of pressure. i have never encountered a system to do this before any help would be greatly appreciated.

Christopher Lee
Manager
AFA Service and Repair
North Charleston, South Carolina, USA