Description
DescriptionRefrigeration System Component Layout:
The air conditioning compressor is of fixed displacement and is engine mounted, driven by the common drive belt via a clutch. Operation of the compressor clutch is controlled, via a relay, by the ECM. A compressor on signal is monitored from the compressor relay to inform the Air Conditioning Control Module (A/CCM) of the compressor status and to facilitate lock detection and error sensing. This compressor rotating signal is generated at the compressor and then compared with engine speed. If the speed ratio is excessive, the compressor clutch will disengage and the LED on the control panel will begin to flash. Refrigerant pressure is monitored by a four-level pressure switch located in the liquid coolant high pressure line. When abnormal pressures, below 2 bar (29 psi) or above 30 bar (435 psi), are sensed by the switch, it provides a signal via the A/CCM to the ECM to disengage the compressor clutch drive. The switch also provides a hard wired signal to the ECM to switch the radiator cooling fans to fast mode (parallel) at 22 bar (319 psi) rising pressure and to slow speed at 17.5 bar (253.75 psi) falling pressure. Slow speed operation of the cooling fans is signalled by the four-level pressure switch to the ECM to operate in slow speed (series) from 12 bar (175 psi) rising pressure and to switch the fans off at 8 bar (116 psi) falling pressure.