Lexus ES300 (1997 year). Manual — part 444
N15622
1
2
N02774
20 msec/Division (Idling)
LOCK IN signal waveform
0 V
0.2 V/Din.
–
DIAGNOSTICS
AIR CONDITIONING SYSTEM
DI–553
705
1997 LEXUS ES300 (RM511U)
2
Check compressor lock sensor.
PREPARATION:
Disconnect compressor lock sensor connector.
CHECK:
Measure resistance between terminals 1 and 2 of compressor
lock sensor connector.
OK:
Resistance: at 20
°
C (68
°
F): 65 – 125
Ω
Reference: Inspection using oscilloscope
During cranking or idling, measure voltage between terminals
LOCK IN and SG of A/C control assembly.
HINT:
The correct waveform appears as shown in the illustration on
the left.
NG
Replace compressor lock sensor.
OK
3
Check harness and connector between A/C control assembly and compressor
lock sensor (See page
NG
Repair or replace harness or connector.
OK
Proceed to next circuit inspection shown on matrix chart (See page
). However, if DTC 22
is displayed, check and replace A/C control assembly.
I00327
A/C Control Assembly
12 V
PSW
A14
9
L–B
IM3
12
Pressure Switch
W–B
EC
L–B
4
1
DI–554
–
DIAGNOSTICS
AIR CONDITIONING SYSTEM
706
1997 LEXUS ES300 (RM511U)
DTC
23
Pressure Switch Circuit
CIRCUIT DESCRIPTION
This pressure switch sends the appropriate signals to the A/C control assembly when the air conditioning
refrigerant pressure drops too low or rises too high. When the A/C control assembly receives these signals,
if outputs signals via the ECM to switch off the compressor relay and turns the magnetic clutch off.
DTC No.
Detection Item
Trouble Area
23
Open in pressure sensor circuit.
Abnormal refrigerant pressure.
below 196 kPa (2.0 kgf/cm
2,
28 psi)
over 3,140 kPa (32.0 kgf/cm
2
, 455 psi)
Pressure switch
Harness or connector between pressure switch and A/C con-
trol assembly.
Refrigerant pipe line.
A/C control assembly.
WIRING DIAGRAM
DI0DE–01
BE3840
I00368
I00370
ON
PSW(+)
(–)
Low Pressure Cut Side
Reference: High Pressure Cut Side
ON (0 V)
225 kPa
196 kPa
OFF (12 V)
2,550 kPa
3,140 kPa
OFF (12 V)
ON (0 V)
I00379
Low Pressure Cut Side
Reference: High Pressure Cut Side
ON (continuity
225 kPa
196 kPa
OFF (no continuity
2,550 kPa
3,140 kPa
OFF (no continuity)
ON (continuity)
–
DIAGNOSTICS
AIR CONDITIONING SYSTEM
DI–555
707
1997 LEXUS ES300 (RM511U)
INSPECTION PROCEDURE
1
Check voltage between terminals PSW of A/C control assembly and body
ground.
PREPARATION:
(a)
Install the manifold gauge set (See page
).
(b)
Turn ignition switch ON.
CHECK:
Check voltage between terminals PSW of A/C control assembly
connector and body ground when air conditioning gas pressure
is changed.
OK:
The voltage changes with gas pressure, as shown in
the diagram below.
OK
Proceed to next circuit inspection shown on
matrix chart (See page
NG
2
Check pressure switch.
PREPARATION:
Disconnect pressure switch connector.
CHECK:
Check continuity between terminals 1 and 4 of pressure switch
when air conditioning gas pressure is changed.
OK:
The continuity changes with gas pressure as shown
below.
NG
Replace pressure switch.
OK
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