DESCRIPTION AND OPERATION
RANGE ROVER 4.57
Fuse 53 (C0583) is connected to the ignition switch (C0099 on Td6 vehicles, C0028 on V8
vehicles) by an R wire. When the ignition switch is turned to the 'ignition' position, current
flows across the switch (C0099 on Td6 vehicles, C0028 on V8 vehicles) to fuse 34 and fuse
2 of the passenger compartment fuse box (C0585) on a G wire. Fuse 34 (C0587) provides
an ignition feed to the ATC ECU (C1629) on a GY wire.
Fuse 2 (C0587) provides an ignition feed to the rear blower relay coil (C2022) on a GY wire.
The rear blower relay is located in the rear fuse box (C2021) and is earthed on an N wire.
Fusible link 5 of the passenger compartment fuse box (C0588) provides a constant battery
feed to fuse 12R in the rear fuse box (C2024) on an R wire. Fuse 12R is connected to the
rear blower relay switch. When the relay is energised, current flows across the closed switch
contacts (C2021) to the rear blower motor control unit (C2282) on a GU then SUY then UG
wire.
Compressor
When compressor operation is required, the ATC ECU (C1629) sends a message to the
Engine Control Module (ECM) via the K bus on a WRY wire. Provided there are no engine
management constraints, the ECM (C0331) responds by increasing throttle angle and
fuelling and returns a signal granting operation of the compressor to the ATC ECU (C1629)
on a BG wire. The ATC ECU (C1630) then provides a feed to the compressor clutch (C0182)
on a BS wire.
For more details of compressor operation, refer to the Air Conditioning section of the
System Description and Operation Workshop manual.
Refrigerant Pressure Sensor
The refrigerant pressure sensor provides the ATC ECU with a pressure input from the high
pressure side of the refrigerant system. The ATC ECU (C1629) provides a 5 V reference
feed to the pressure sensor (C1610) on a GY wire. The pressure sensor (C1610) returns a
signal voltage of between 0 V and 5 V, depending upon system pressure, to the ATC ECU
(C1629) on a BS wire. The ATC ECU (C1629) provides an earth path for the pressure
sensor (C1610) on an NB wire.
Evaporator Temperature Sensor
The evaporator temperature sensor is a Negative Temperature Coefficient (NTC) sensor.
The ATC ECU (C0923) provides a feed to the evaporator temperature sensor (C0417) on
an NB wire. By measuring the voltage returned on a YB wire, the ATC ECU (C0923) can
determine evaporator temperature.
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