WARNING: This page is about a different car, the 2001 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: 4.3L VIN W, Compressor Circuit
Fig 2: 4.3L VIN W, Heater Circuit
Fig 3: 4.3L VIN W, Manual A/C Circuit, Cargo Van
Fig 4: 4.3L VIN W, Manual A/C Circuit, Passenger Van