Toyota Repair: inop a/c at idle, emission control system, toyota 4x4

Question
Hi there can't figure out why my a/c works at all phases except idle.Also what do the abbreviations VSV for AS stand for? I own a 1989 toyota 4x4 p/u 22RE Thanks

Answer
The freon level may be too low to engage the compressor at idle, this can be checked by connecting pressure gauges to the system to read the pressures, this should be done by a qualified a/c technician, VSV stands for vacuum switching valve, the AS may refer to air suction which is part of the emission control system.