Compressor controls

COMPRESSOR CONTROLS

COMPRESSOR CONTROLS Compressor Control (300Tdi without EDC)

With the Ignition Switch (X134) in position II, battery voltage is applied to the Ignition Load Relay (K127). The relay is energized, applying battery voltage to the Compressor Clutch Relay (K108). When the Front Fan Speed Switch (X247) is turned to positions I, II, III, or IV and the Front A/C Switch (X225) is turned On, ground is provided to terminal 86 of the Compressor Clutch Relay (K108) through the closed contacts of the A/C Dual Pressure Switch (X102), the Front A/C Evaporator Temperature Switch (X101), and the Compressor Clutch Cut-out Switch (X259). The relay is energized, applying battery voltage to the Compressor Clutch (K107). Compressor Clutch operation is now controlled by the status of the A/C Dual Pressure Switch (X102), the Front A/C Evaporator Temperature Switch (X101), and the Compressor Clutch Cut-out Switch (X259). The Front A/C Evaporator Temperature Switch (X101) is fitted in the airflow out of the front evaporator to sense the temperaure of the exterior fins. Should ice begin to form, due to low temperature, the switch will open. The A/C Dual Pressure Switch (X102) monitors refrigerant pressure in the high pressure line, should pressure become too high or too low the switch will open. When one or more of these switches open, the ground supply to terminal 86 of the Compressor Clutch Relay (K108) will be interrupted. The relay de-energizes, removing battery voltage from the Compressor Clutch (K107), disengaging the Compressor.

Rear A/C Refrigerant Control Valve

When front A/C has been selected and the Compressor Clutch (K107) is engaged, the Compressor Clutch Relay (K108) is energised and voltage is applied on the BG wires to the Rear A/C Refrigerant Control Valve (K207). When rear A/C is selected a ground signal is applied to the Rear A/C Switch Amplifier (Z216). The Rear A/C Switch Amplifier (Z216) then applies a ground signal to energise the Rear A/C Control Relay (K194 ) and the Rear A/C Fan Speed Relay (K205). When the Passenger’s Rear Fan Speed Switch (X246) is in any position other than Off, ground is applied to the Rear A/C Refrigerant Control Valve (K207) through the closed contacts of the Passengers Rear Fan Speed Switch (X246), BR wire, closed contacts of the Rear A/C Fan Speed Relay (K205), PG wire, UB wire, Rear A/C Refrigerant Control Valve Diode

E L E C T R I C A L T R O U B L E S H O O T I N G

2

(Z228), P wire, closed contacts of the Rear A/C Evaporator Temperature Switch (X260), and the RG wire. The Rear A/C Evaporator Temperature Switch (X260) senses the temperature of the exterior fins. Should ice begin to form due to low temperature, the switch will open and the ground supply to the Rear A/C Refrigerant Control Valve (K207) will then be interrupted. The valve de-energises and refrigerant flow is interrupted. The Rear A/C Refrigerant Control Valve (K207) will also be de-energised if one or more of the following conditions occurs: The Front A/C Switch (X225) has been turned 
OFF. The Front Fan Speed Switch (X247) has been 
turned OFF. The Rear A/C switches have been turned OFF. 
The Passenger’s Rear Fan Speed Switch 
(X246) has been turned OFF. The ECM determines that compressor clutch 
operation is no longer required. Compressor Clutch (K107) operation has been 
disabled by the A/C Dual Pressure Switch (X102) or the Front A/C Evaporator Temperature Switch (X101). Compressor Clutch (K107) operation has been 
disabled by the Compressor Clutch Cut-Out Switch (X259) (300Tdi Without EDC Only).

M A N U A L