Chevy express van dual a/c problems

Have a 2004 Chevy Express van with factory front and rear a/c. Recently, rear a/c quit but front works fine. Rear a/c blows air but no cooling. Found hot water coil shut off valve leaking hot water to coil in rear and removed valve, with the hope that this would solve the problem. Still no a/c to rear but front works fine. Suction operating pressure seems fine (r-134 freon)(what is proper # for r-134 suction side?), compressor not short cycling and suction line for front is very cold, discharge air is about 46 degrees. Front and rear a/c coils have common suction @ compressor but cannot see liquid line, do not know if rear has factory equipped solenoid valve, preventing liquid freon to go to back, though suction line and liquid lines from rear very hot. Someone out there fluent in Chevy dual air?