Freelander System Description and Operation
AIR CONDITIONING
82-18
DESCRIPTION AND OPERATION
Compressor Clutch Relay
The compressor clutch relay switches power to the compressor clutch under the control of the ECM. The relay is
located in the engine compartment fusebox. The compressor clutch is energized to engage and de-energized to
disengage.
Compressor
Operation of the clutch is controlled by the engine control module (ECM). To protect the refrigerant system from
unacceptably high pressure, a pressure relief valve is installed in the outlet side of the compressor. The pressure relief
valve is set to operate at 3430 kPa (497.5 lbf.in) and vents excess pressure into the engine compartment.
The ECM controls the operation of the compressor via the compressor clutch relay in the engine compartment fuse
box. When the A/C switch is used to request air conditioning, the ECM energises the compressor clutch relay to supply
a power feed to the compressor clutch. Engagement of the compressor clutch is withheld, or discontinued, if
refrigerant pressure exceeds upper or lower pressure limits:
l
The upper pressure limit is 29 bar (421 lbf/in
2
), e.g. due to a blockage. Compressor engagement is re-enabled
when the pressure decreases to 23 bar (334 lbf.in
2
).
l
The lower pressure limit is 1.6 bar (23.2 lbf/in
2
), e.g. due to a leak. Compressor engagement is re-enabled when
the pressure increases to 2.0 bar (29.0 lbf/in
2
).
Cooling and Condenser Fans
1 Cooling and condenser fans
2 Cooling/condenser fan controller