Operation (page 2 of 2)

The compressor will continue to operate and cold air will be blown into the passenger compartment, until the air temperature measured in the vicinity of the evaporator, falls below 2°C. At this temperature, the thermo switch will open and power will be removed from the blower motor and compressor magnetic clutch relays. When the temperature rises above 5°C again, the thermo switch contacts will close and power to the blower and clutch relays will be restored. Power will also be removed from the air conditioning system by the ECM, if the engine coolant temperature rises above 120°C. Operation of the air conditioner will be inhibited until the temperature falls to 116°C.

A lamp will light in the A/C switch (when the switch is operated and the blower is enabled), by power fed on a B/Y wire from fuse 13 in the passenger compartment fuse box. Background illumination for the switch is provided when the vehicle sidelights are on, by a feed from fuse 19 on an R/B wire. The return path for this lamp is via a B wire.

The Trinary Pressure Switch - K, T and L series only The Trinary switch responds to refrigerant pressure on three levels:

The high and low switches protect the system from damage by excessive refrigerant pressure or from refrigerant loss. If either switch operates, the compressor magnetic clutch is dis-engaged and the fans are switched OFF. Provided all the other conditions necessary for air conditioner function remain true, when pressure is restored to a value between 240 and 2100 KPa, the switches will revert to normal and the air conditioner will resume operation.