1991 LEXUS SC400 engine

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Page 59 of 4087

LEXUS SC400 1991  Service Repair Manual 
4.  INSPECT REFRIGERATION SYSTEM FOR LEAKSHINT: After evacuating the air in system, check the system for
leakage.
(a)  Open the high pressure hand valve to charge the system with refrigerant.
(b) Whe

Page 60 of 4087

LEXUS SC400 1991  Service Repair Manual 
6.  CHARGE PARTIALLY REFRIGERATION SYSTEM WITHREFRIGERANT (VAPOR)
HINT: This step is used to charge the system through the low
pressure side with refrigerant in a vapor state.
NOTICE: Do not open the

Page 67 of 4087

LEXUS SC400 1991  Service Repair Manual 
DIAGNOSTIC CODE CHART
If a malfunction code is displayed during the diagnostic code check (sens\
or check), check the circuit listed for
that code in the table below (Proceed to the page given for th

Page 71 of 4087

LEXUS SC400 1991  Service Repair Manual 
STANDARD VALUE OF ECU TERMINAL
TerminalsSymbolsWiringColorConditionStandardValue
A14±1A14±7B ER W±BIG OFF10 ~ 14 V
A14±2 A14±3MH MCV R±YIG OFF13 ~ 19  
A14±4A14±5MFRSMRECG G±RIG OF

Page 77 of 4087

LEXUS SC400 1991  Service Repair Manual 
LOCATION OF CONNECTORS
LOCATION OF CONNECTORS IN ENGINE COMPARTMENT
AC±38±
AIR CONDITIONING SYSTEM Troubleshooting 
WhereEverybodyKnowsYourName

Page 89 of 4087

LEXUS SC400 1991  Service Repair Manual 
Diag. Code 14Water Temperature Sensor Circuit
CIRCUIT DESCRIPTION
This sensor detects the coolant temperature and sends the appropriate signal\
s to the air conditioner
control assembly. These signal

Page 93 of 4087

LEXUS SC400 1991  Service Repair Manual 
Diag. Code 22Compressor Lock Sensor Circuit
CIRCUIT DESCRIPTION
This sensor sends 4 pulses per engine revolution to the air conditioner cont\
rol assembly.
If the number ratio of the compressor speed

Page 94 of 4087

LEXUS SC400 1991  Service Repair Manual 
INSPECTION PROCEDURE
Check compressor
(1). Check compressor drive belt tension (See page AC-104).
(2). Check if the compressor does not lock during with engine started and blo\
wer switch and A/C swi