Page 1985 of 2493

Refrigeration System
REFRIGERATION CYCLENJHA0121Refrigerant FlowNJHA0121S01The refrigerant flows in the standard pattern, that is, through the compressor, the condenser, the liquid tank,
through the evaporator, and back to the compressor. The refrigerant evaporation through the evaporator coil
is controlled by an externally equalized expansion valve, located inside the heater & cooling unit.
Freeze ProtectionNJHA0121S02The compressor cycles go on and off to maintain the evaporator temperature within a specified range. When
the evaporator coil temperature falls below a specified point, the thermo control amplifier interrupts the com-
pressor operation. When the evaporator coil temperature rises above the specification, the thermo control
amplifier allows compressor operation.
Refrigerant System ProtectionNJHA0121S03Refrigerant Pressure SensorNJHA0121S0303The refrigerant system is protected against excessively high or low pressures by the refrigerant pressure
sensor, located on the liquid tank. If the system pressure rises above, or falls below the specifications, the
refrigerant pressure sensor detects the pressure inside the refrigerant line and sends the voltage signal to the
ECM. ECM makes the A/C relay go OFF and stops the compressor when pressure on the high pressure side
detected by refrigerant pressure sensor is over about 2,746 kPa (27.5 bar, 28 kg/cm
2, 398 psi) or below about
137 kPa (1.37 bar, 1.4 kg/cm2, 20 psi).
Dual-pressure Switch
NJHA0121S0304The refrigerant system is protected against excessively high or low pressures by the dual-pressure switch,
located on the liquid tank. If the pressure falls out of specifications, the switch opens to interrupt compressor
operation.
Pressure Relief Valve
NJHA0121S0302The refrigerant system is also protected by a pressure relief valve, located in the rear head of the compres-
sor. When the pressure of refrigerant in the system increases to an abnormal level [more than 3,727 kPa (37.3
bar, 38 kg/cm
2, 540 psi)], the release port on the pressure relief valve automatically opens and releases
refrigerant into the atmosphere.
RHA682H
DESCRIPTION
Refrigeration System
HA-13
Page 2034 of 2493
MAGNET CLUTCH CIRCUIT (FOR QG ENGINE)=NJHA0156SYMPTOM:
+Magnet clutch does not engage when A/C switch and fan
switch are ON.
1 CHECK POWER SUPPLY FOR COMPRESSOR
Disconnect compressor harness connector.
Do approx. 12 volts exist between compressor harness terminal No. 1 and body ground?
RHA794H
YesorNo
Ye s©GO TO 2.
No©Disconnect A/C relay. GO TO 3.
2 CHECK MAGNET CLUTCH COIL
OK or NG
NG©Replace magnet clutch. Refer to HA-91.
3 CHECK CIRCUIT CONTINUITY BETWEEN A/C RELAY AND COMPRESSOR HARNESS
Check circuit continuity between A/C relay harness terminal No. 3 and compressor harness terminal No. 1.
RHA634H
Continuity should exist.
If OK, check harness for short.
OK or NG
OK©GO TO 4.
NG©Repair harness or connector.
TROUBLE DIAGNOSES
Magnet Clutch (Cont'd)
HA-62
Page 2035 of 2493
4 CHECK POWER SUPPLY FOR A/C RELAY
Disconnect A/C relay.
Do approx. 12 volts exist between A/C relay harness terminal Nos. 1, 5 and body ground?
RHA635H
YesorNo
Ye s©GO TO 5.
No©Check power supply circuit and 10A (No. 15) fuse at fuse block. Refer to Sedan: EL-23,
Hatchback: EL-12, ªWiring Diagram Ð POWER к.
5 CHECK A/C RELAY AFTER DISCONNECTING IT
Refer to HA-72.
OK or NG
OK©Reconnect A/C relay. GO TO 6.
NG©Replace A/C relay.
6 CHECK COIL SIDE CIRCUIT OF A/C RELAY
Do approx. 12 volts exist between ECM harness terminal No. 23 and body ground?
NHA510
YesorNo
Ye s©GO TO 8.
No©Disconnect A/C relay. Disconnect ECM harness connector. GO TO 7.
TROUBLE DIAGNOSES
Magnet Clutch (Cont'd)
HA-63
Page 2036 of 2493
7 CHECK CIRCUIT CONTINUITY BETWEEN A/C RELAY AND ECM HARNESS
Check circuit continuity between A/C relay harness terminal No. 2 and ECM harness terminal No. 23.
NHA511
Continuity should exist.
If OK, check harness for short.
OK or NG
OK©Check ECM. Refer to EC-132 (QG), ªECM Terminals and Reference Valueº.
NG©Repair harness or connector.
8 CHECK VOLTAGE FOR ECM
Do approx. 12 volts exist between ECM harness terminal No. 51 and body ground?
NHA512
YesorNo
Ye s©GO TO 9.
No©Check ECM. Refer to EC-132 (QG), EC-554 (YD), ªECM Terminals and Reference
Valueº.
9 CHECK REFRIGERANT PRESSURE SENSOR
Refer to HA-73.
OK or NG
OK©GO TO 10.
NG©Replace refrigerant pressure sensor.
10 CHECK A/C SWITCH
Refer to HA-73.
OK or NG
OK©GO TO 11.
NG©Replace heater control panel.
TROUBLE DIAGNOSES
Magnet Clutch (Cont'd)
HA-64
Page 2039 of 2493
16 CHECK BODY GROUND CIRCUIT
Check circuit continuity between heater control panel harness terminal No. 9 or 13 and body ground.
NHA506
Continuity should exist.
If OK, check harness for short.
OK or NG
OK©INSPECTION END
NG©Repair harness or connector.
MAGNET CLUTCH CIRCUIT (FOR YD ENGINE)NJHA0203SYMPTOM:
+Magnet clutch does not engage when A/C switch and fan
switch are ON.
1 CHECK POWER SUPPLY FOR COMPRESSOR
Disconnect compressor harness connector.
Do approx. 12 volts exist between compressor harness terminal No. 1 and body ground?
RHA794H
YesorNo
Ye s©GO TO 2.
No©Disconnect A/C relay. GO TO 3.
2 CHECK MAGNET CLUTCH COIL
OK or NG
NG©Replace magnet clutch. Refer to HA-91.
TROUBLE DIAGNOSES
Magnet Clutch (Cont'd)
HA-67
Page 2040 of 2493
3 CHECK CIRCUIT CONTINUITY BETWEEN A/C RELAY AND COMPRESSOR HARNESS
Check circuit continuity between A/C relay harness terminal No. 3 and compressor harness terminal No. 1.
RHA634H
Continuity should exist.
If OK, check harness for short.
OK or NG
OK©GO TO 4.
NG©Repair harness or connector.
4 CHECK POWER SUPPLY FOR A/C RELAY
Disconnect A/C relay.
Do approx. 12 volts exist between A/C relay harness terminal Nos. 1, 5 and body ground?
RHA635H
YesorNo
Ye s©GO TO 5.
No©Check power supply circuit and 10A (No. 15) fuse at fuse block. Refer to Sedan: EL-23,
Hatchback: EL-12, ªWiring Diagram Ð POWER к.
5 CHECK A/C RELAY AFTER DISCONNECTING IT
Refer to HA-72.
OK or NG
OK©Reconnect A/C relay. GO TO 6.
NG©Replace A/C relay.
TROUBLE DIAGNOSES
Magnet Clutch (Cont'd)
HA-68
Page 2041 of 2493
6 CHECK COIL SIDE CIRCUIT OF A/C RELAY
Do approx. 12 volts exist between ECM harness terminal No. 204 and body ground?
NHA517
YesorNo
Ye s©GO TO 8.
No©Disconnect A/C relay. Disconnect ECM harness connector. GO TO 7.
7 CHECK CIRCUIT CONTINUITY BETWEEN A/C RELAY AND ECM HARNESS
Check circuit continuity between A/C relay harness terminal No. 2 and ECM harness terminal No. 204.
NHA518
Continuity should exist.
If OK, check harness for short.
OK or NG
OK©Check ECM. Refer to EC-132 (QG), EC-554 (YD), ªECM Terminals and Reference
Valueº.
NG©Repair harness or connector.
TROUBLE DIAGNOSES
Magnet Clutch (Cont'd)
HA-69
Page 2044 of 2493
14 CHECK FAN SWITCH
Refer to HA-60.
OK or NG
OK©GO TO 15.
NG©Replace fan switch.
15 CHECK BODY GROUND CIRCUIT
Check circuit continuity between heater control panel harness terminal No. 13 and body ground.
RHA778H
Continuity should exist.
If OK, check harness for short.
OK or NG
OK©INSPECTION END.
NG©Repair harness or connector.
RHA638H
ELECTRICAL COMPONENT INSPECTIONNJHA0192A/C RelayNJHA0192S01Check continuity between terminal Nos. 3 and 5.
Conditions Continuity
12V direct current supply between terminal Nos. 1 and 2 Yes
No current supply No
If NG, replace relay.
TROUBLE DIAGNOSES
Magnet Clutch (Cont'd)
HA-72