Page 65 of 2543

Remove magnetic clutch relay from R/B No. 2.
Check continuity between each pair of terminals
shown below of magnetic clutch relay.
Terminals 1 and 2
Terminals 3 and 5
Terminals 3 and 5
No continuity
Continuity
Replace magnetic relay.
Check and replace the ECM.
Repair or replace harness or connector.
A/C SwitchVoltage
ON
OFF
Check for open and short in harness and connector between the ECM and
battery (See page IN±30).
Approx. 1.3. V
Approx. 75
Battery positive voltage
Check magnetic clutch relay.
Check voltage between terminal ACMG of ECM and body ground.
1. Apply battery positive voltage between terminals
1 and 2.
2. Check continuity between terminals 3 and 5.
1. Remove the ECM with connectors still con
nected.
2. Turn ignition switch on.
1. Turn fan speed control dial (Lo, Med or Hi).
2. Measure voltage between terminal ACMG of the
ECM connector and body ground.
Proceed to next circuit inspection shown on matrix
chart (See page AC±26).
~ 1.3 V
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±65
Page 66 of 2543
A C Control Assembly Circuit
CIRCUIT DESCRIPTION
This circuit includes the control switch circuit and the LED circuit in the A/C control Assembly.
The A/C amplifier always searches which switch is operated and drives the LED according to A/C control opera-
tion or diagnostic sensor check operation.
AC±66± AIR CONDITIONING SYSTEMTROUBLESHOOTING
Page 67 of 2543
INSPECTION PROCEDURE
Check the each LED lights up when the applicable switch is operated.
Proceed to next circuit inspection shown on matrix
chart (See page AC±26).
Check voltage between terminal for LED (OFF) and terminal H12±9 of
A/C control assembly.
Check continuity of harness between A/C amplifier and A/C control
assembly.
Go to step
Repair or replace harness or connector.
Repair or replace A/C control assembly.
Switch
ON
OFF
Below 1.0 V
10 ~ 14 V
Voltage
All LED OFFCheck IG switch circuit.
1. Push the switch on or OFF.
2. Check voltage between terminal for the LED
(OFF) and terminal H12±9 of A/C control as
sembly.
1. Push each switch or turn fan sped dial on the
A/C control assembly.
2. Check LED lighting according to switch operation.
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±67
Page 68 of 2543
Repair or replace A/C control assembly.
Check and replace A/C amplifier.
SwitchCheck result
ON
OFFNo continuity
Continuity
Remove A/C control assembly and disconnect con
nectors.
Check continuity of switch circuit in A/C control assembly.
1. Push the control switch on or Off.
2. Check continuity between terminals as follows.
FAND ± : Turn fan speed dial counterclockwise.
FAND + : Turn fan speed dial clockwise.
AC±68± AIR CONDITIONING SYSTEMTROUBLESHOOTING
Page 69 of 2543
Temperature Set Dial Circuit
CIRCUIT DESCRIPTION
When temperature set dial is turned, the voltage of TSET terminal will change. A/C amplifier searches for this
change and controls the room temperature according to the temperature set.
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±69
Page 70 of 2543
INSPECTION PROCEDURE
Check voltage of TSET terminal on A/C amplifier.
Check voltage of terminal on A/C control assembly.
Check harness and connectors for S5 and SG signal.
Proceed to next circuit inspection shown on
matrix chart (See page AC±26).
Replace A/C control assembly.
Repair or replace harness or connectors between
A/C amplifier and A/C control assembly.
Repair or replace harness or connectors between
A/C amplifier and A/C control assembly.
VoltageCheck Terminals
VoltageSet Temperature
1. Turn temperature set dial.
2. Check voltage between terminals TSET and SG
of A/C amplifier.
Remove A/C amplifier with connectors still connected.
Remove A/C control assembly with connectors still
connected.
Check voltage between following terminal and H12±9
(GND) of A/C control assembly connectors.
AC±70± AIR CONDITIONING SYSTEMTROUBLESHOOTING
Page 71 of 2543
REFRIGERANT SYSTEM INSPECTION WITH MANIFOLD GAUGE SET
This is a method in which the trouble is located by using a manifold gauge set.
(See ªUSE OF MANIFOLD GAUGE SETº on page AC±11)
Read the manifold gauge pressure when the following conditions are established:
(a) Temperature at the air inlet with the switch set at RECIRC is 30±35 °C (86±95 °F)
(b) Engine running at 1,500 rpm
(c) Blower speed control switch set at high
(d) Temperature control set at max. cool
HINT: It should be noted that the gauge indications may vary slightly due to ambient temperature condi-
tions.
1. NORMALLY FUNCTIONING REFRIGERATION SYSTEM
Gauge reading:
Low pressure side:
0.15±0.25 MPa (1.5±2.5 kgf/cm
2)
High pressure side:
1.37±1.57 MPa (14±16 kgf/cm
2)
± AIR CONDITIONING SYSTEMTROUBLESHOOTINGAC±71
Page 72 of 2543

2. MOISTURE PRESENT IN REFRIGERATION SYSTEM
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy
During operation, pres±
sure on low pressure
side sometimes
becomes a vacuum and
sometimes normalMoisture entered in re±
frigeration system
freezes at expansion
valve orifice and tem±
porarily stops cycle, but
normal state is restored
after a time when the ice
melts(1) Replace receiver/drier
(2) Remove moisture in
cycle through repeat±
edly evacuating air
(3) Charge new refriger±
ant to proper amountDrier in oversaturated
state
Moisture in refrigeration
system freezes at ex±
pansion valve orifice
and blocks circulation of
refrigerant
Condition: Periodically cools and then fails to cool
3. INSUFFICIENT REFRIGERANT
Symptom seen in
refrigeration system
Condition: insufficient cooling
Probable causeDiagnosisRemedy
Pressure low on both
low and high pressure
sides
Bubbles seen in sight
glass continuously
insufficient cooling
performanceGas leakage at some
place in refrigeration
systemInsufficient refrigerant
in system
Refrigerant leaking(1) Check for gas leak
age with leak detec±
tor and repair if nec±
essary
(2) Charge refrigerant to
proper amount
(3) If pressure indicated
value is near 0 when
connected to gauge,
create the vacuum
after inspecting and
repairing the location
of the leak
AC±72± AIR CONDITIONING SYSTEMTROUBLESHOOTING