Subaru XT 1988 Service Manual page 1063

Pulser Amplifier
FUNCTION
o
o
o
Fig. 88
Terminal
No. Cable color
1
RY
2
y
3
R
4
G
5
RB
6
LB
AIR CONDITIONING SYSTEM
4-7
Destination
Power supply
Ignition coil (-)
Pulse sensor (-)
Pulse sensor
(+)
Magnetic clutch
drive relay coil
Ground
L4-539
REMOVAL AND INSTALLATION
1} Remove instrument panel lid and pocket.
2} Remove front shelf.
3} Disconnect body harness (6-pole connector) from ampli·
fier.
4} Loosen the bolt installing evaporator and remove pulser
amplifier.
Fig. 89
5) Install in the reverse order of removal.
Description
Supplies current to the pulser amplifier through the air conditioner
switch and triple (low-pressure) switch for the purpose of acti-
vating accessories.
Transmits engine rpms to the pulser amplifier in pulse form.
Transmits compressor rpms to the pulser amplifier for comparison
with ignition pulses.
When compressor rpms drop below 75 to 80% of engine rpms, the
RB's grounding circuit will open.
When the thermostat activates to close the ground circuit with the
air conditioner switch "ON", the clutch will engage.
When compressor is locked, the thermostat activates to open the
ground circuit, disengaging the clutch.
The thermostat opens and closes the ground circuit, depending on
the temperature of the evaporator.
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