Service Hints - Toyota AT180 Series Repair Manual

RADIATOR FAN AND AIR CONDITIONER (AUTOMATIC AIR CONDITIONER, FOR PUSH TYPE OF BLOWER CONTROL SW)
SYSTEM OUTLINE
6. AIR CONDITIONER OPERATION
THE A/C AMPLIFIER RECEIVES VARIOUS SIGNALS, THE ENGINE RPM SIGNAL FROM THE IGNITER, OUTLET TEMPERATURE SIGNAL
FROM THE A/C THERMISTER, COOLANT TEMPERATURE FROM THE WATER TEMP. SENSOR, AND THE LOCK SIGNAL FROM THE A/C
COMPRESSOR, ETC.
WHEN THE ENGINE IS STARTED AND THE A/C SW (A/C CONTROL ASSEMBLY) IS TURNED ON, A SIGNAL IS INPUT TO TERMINAL A/C
S/W OF A/C AUTO AMPLIFIER FROM TERMINAL C12 OF A/C CONTROL ASSEMBLY. WHEN THIS HAPPENS, A SIGNALS IS OUTPUT
FROM TERMINAL A/C OF A/C AUTO AMPLIFIER TO TERMINAL 3 OF A/C AMPLIFIER.
AS A RESULT, THE CURRENT FLOWING FROM TERMINAL 3 OF A/C MAGNET CLUTCH RELAY TO TERMINAL 8 OF A/C AMPLIFIER
FLOWS FROM TERMINAL 15 OF A/C AMPLIFIER TO GROUND AND TURNS IN THE MAGNET CLUTCH RELAY.
BECAUSE THE MAGNET CLUTCH IS ON, THE A/C COMPRESSOR OPERATES, CAUSING THE CURRENT FLOWING FROM A/C IDLE–UP
VSV TO TERMINAL 6 OF A/C AMPLIFIER TO FLOW TO TERMINAL 15 OF A/C AMPLIFIER
AVOID LOWERING THE ENGINE RPM DURING AIR CONDITIONER OPERATION.
WHEN ANY OF THE FOLLOWING SIGNALS ARE INPUT TO THE A/C AMPLIFIER, THE AMPLIFIER OPERATES TO TURN OFF THE AIR
CONDITIONER:
∗ ENGINE HIGH RPM SIGNAL
∗ COOLANT HIGH TEMP. SIGNAL IS HIGH.
∗ A SIGNAL THAT THE TEMPERATURE AT THE AIR OUTLET IS LOW.
∗ A SIGNAL THAT THERE IS A LARGE DIFFERENCE BETWEEN ENGINE RPM AND COMPRESSOR RPM
∗ A SIGNAL THAT THE REFRIGERANT PRESSURE IS ABNORMALLY HIGH OR LOW.

SERVICE HINTS

A/C MAGNET CLUTCH
A 4
4–GROUND : APPROX. 3.7 W
A/C PRESSURE SW
A 5
3–2 : OPEN ABOVE APPROX. 13.5 KG/CM
CLOSED BELOW APPROX. 10 KG/CM
1–4 : OPEN WITH PRESSURE LESS THAN 2.1 KG/CM
A/C AMPLIFIER
A17
8–15 : CONTINUITY WITH A/C SW (A/C CONTROL ASSEMBLY) ON AND IGNITION SW AT ON POSITION
14–15 : ALWAYS CONTINUITY
14–GROUND: ALWAYS CONTINUITY
15–GROUND: ALWAYS CONTINUITY
13–GROUND: APPROX. 12 VOLTS WITH IGNITION SW ON
A/C ROOM TEMP. SENSOR
A23
1–2 : APPROX. 1.7 KΩ AT 25°C (77°F)
A/C THERMISTOR
A26
1–2, 3–4 : APPROX. 4852 Ω AT 0°C (32°F)
APPROX. 2341 Ω AT 15°C (39°F)
APPROX. 1500 Ω AT 25°C (77°F)
AIR MIX CONTROL SERVO MOTOR
A29
2–GROUND : APPROX. 12 VOLTS WITH TEMPERATURE CONTROL VOLUME AT WARM TO COOL POSITION
6–GROUND : APPROX. 12 VOLTS WITH TEMPERATURE CONTROL VOLUME AT COOL TO WARM POSITION
1–3 : ALWAYS APPROX. 6 KΩ
AUTO A/C AMPLIFIER
A32(A), A33(B) A34(C)
B–GROUND : APPROX. 12 VOLTS
IG–GROUND : APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
HR–GROUND : CONTINUITY WITH BLOWER SW (A/C CONTROL ASSEMBLY) ON OR AUTO SW ON
S5–GROUND : APPROX. 5 VOLTS WITH IGNITION SW ON
SG–GROUND : ALWAYS CONTINUITY
REC–GROUND : APPROX. 12 VOLTS WITH A/C CONTROL ASSEMBLY AT RECIRC POSITION
FRS–GROUND : APPROX. 12 VOLTS WITH A/C CONTROL ASSEMBLY AT FRESH POSITION
GND–GROUND: ALWAYS CONTINUITY
BLOWER CONTROL RELAY
B 3
3–4 : CLOSED WITH BLOWER SW (A/C CONTROL ASSEMBLY) AT ON POSITION
BLOWER RESISTOR
B 6
1–4 : APPROX. 2.4 Ω
WATER TEMP. SW (FOR FANS CONTROL)
W 4
1–2 : OPEN ABOVE APPROX. 90°C (194°F)
CLOSED BELOW APPROX. 83°C (181.4°F)
188
(192 PSI, 1323 KPA)
2
(142 PSI, 980 KPA)
2
2 (
30 PSI, 206 KPA ) OR ABOVE 27 KG/CM
GROUND, AND TURNS ON THE VSV TO
2
(384 PSI, 2648 KPA)