13-82
FUEL SYSTEM
On-vehicle Inspection of MPI Components
AIR CONDITIONER SWITCH AND POWER RELAY
Air
Air conditioner
control unit
Air conditioner
compressor lock
controller
r
Engine control unit
Dual pressure
switch
Air conditioner
compressor
Engine control
connector
OPERATION
l
The air conditioner switch applies the battery voltage to the engine control unit when the air conditioner is
turned on.
l
When the air conditioner ON signal is input, the engine control unit drives the idle speed control servo and
turns ON the power transistor. As a result, the air conditioner power relay coil is energized to turn on the
relay switch, which activates the air compressor magnetic clutch.
TROUBLESHOOTING HINTS
If the air compressor magnet clutch is not activated when the air conditioner switch is turned on during idling,
faulty air conditioner control system is suspected.
INSPECTION
Using Multi-use Tester
AIR CONDITIONER SWITCH
Function
Item No. Data display
Check condition
Air conditioner switch Normal indication
Data reading 28
Switch state
Engine: Idling (air
OFF
OFF
compressor to be running
when air conditioner
ON
ON
switch is ON)
TSB Revision
Summary of Contents for 3000GT 1991
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