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Control System (HVAC): Diagnosis Mazda CX-7 I facelift

Automatic HVAC System 11 illustrations ~570 words

AIR MIX ACTUATOR INSPECTION

CAUTIONIf the lever position exceeds the operation range shown in the figure, the circuit in the actuator could be damaged. Always perform an actuator operation with the lever movement within the range shown in the figure.

Scheme 7

Scheme 7
Scheme 7

Scheme 8

Scheme 8
Scheme 8

Scheme 9

Scheme 9
Scheme 9
  1. Connect battery positive voltage to terminal D or F and ground to terminal F or D of the air mix actuator.
  2. Verify that the air mix actuator operates as shown below. If there is any malfunction, replace the air mix actuator. CONNECTION MOVEMENT REFERENCE Connection Movement B+ GND D F HOT --> COLD F D COLD --> HOT
  3. Verify that the resistance between the terminals of the air mix actuator are as shown in the graph. If there is any malfunction, replace the air mix actuator.

AIRFLOW MODE ACTUATOR INSPECTION

CAUTIONIf the lever position exceeds the operation range shown in the figure, the circuit in the actuator could be damaged. Always perform an actuator operation inspection with the lever movement within the range shown in the figure.

Scheme 10

Scheme 10
Scheme 10

Scheme 11

Scheme 11
Scheme 11

Scheme 12

Scheme 12
Scheme 12
  1. Connect battery positive voltage to terminal D or F and ground to terminal F or D of the airflow mode actuator.
  2. Verify that the airflow mode actuator operates as shown below. If there is any malfunction, replace the airflow mode actuator. CONNECTION MOVEMENT REFERENCE Connection Movement B+ GND D F DEFROSTER --> VENT F D VENT --> DEFROSTER
  3. Verify that the resistance between the terminals of the airflow mode actuator is as shown in the graph. If there is any malfunction, replace the airflow mode actuator.

AMBIENT TEMPERATURE SENSOR INSPECTION

Note. Ambient temperature sensor does not detect a sudden change in temperature sensitively caused by driving or stopping the vehicle to stabilize the control of the full-auto air conditioner. Therefore, the measured value may differ from the original value when the resistance of the ambient temperature sensor is measured immediately after the removal.

Scheme 13

Scheme 13: AMBIENT TEMPERATURE SENSOR INSPECTION
Scheme 13: AMBIENT TEMPERATURE SENSOR INSPECTION
  1. After removing the ambient temperature sensor, leave it to the inspection place for 30 min or more.
  2. Measure the temperature around the ambient temperature sensor.
  3. Measure the resistance between terminals of the ambient temperature sensor. If the resistance is not as shown in the graph, replace the ambient temperature sensor.

CLIMATE CONTROL UNIT INSPECTION [FULL-AUTO AIR CONDITIONER]

  1. Remove the climate control unit. (See «CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER]»(ref-343768-S30108057342009101500000) .)
  2. Install the audio unit. (See «AUDIO UNIT REMOVAL/INSTALLATION»(ref-343789-S01824972822009101500000) ).
  3. Connect the climate control unit connector.
  4. Connect the negative (-) lead of the tester to body ground.
  5. Turn the ignition switch to the ON position.
  6. By inserting the positive (+) lead of the tester into each climate control unit terminal, measure the voltage according to the terminal voltage table. If there is any malfunction, inspect the parts under "Inspection item (s)". If the parts under "Inspection item (s)" are found to be normal (except for terminal T), replace the climate control unit. For terminal T, first try replacing the power MOS FET. If there is still any malfunction, replace the climate control unit.

Scheme 14

Scheme 14: Terminal Voltage Table (Reference)
Scheme 14: Terminal Voltage Table (Reference)
TerminalSignal nameConnected toMeasurement conditionVoltage (V)Inspection item (s)
ACommunication
BCommunication
CSensor GNDAmbient temperature sensor Passenger compartment temperature sensor Evaporator temperature sensor Air mix actuator Airflow mode actuatorUnder any condition1.0 or lessClimate control unit: terminal voltage (D)
DGNDBody groundUnder any condition1.0 or lessWiring harness: continuity (Climate control unit-GND: D-GND)
ESolar radiation sensor inputSolar radiation sensorFluorescent light shined directly on the solar radiation sensor0.1-0.45Wiring harness: continuity (Climate control unit-solar radiation sensor: E-B, J-A) Climate control unit: terminal voltage (J) Solar radiation sensor
Blocking light to solar radiation sensor0.1 or less
FEvaporator temperature sensor inputEvaporator temperature sensorCompared with temperature detected by evaporator temperature sensorRefer to graph 3 ( see scheme 56)Wiring harness: continuity (Climate control unit-evaporator temperature sensor: F-B, C-A) Wiring harness: short circuit (Climate control unit-evaporator temperature sensor: F-B) Evaporator temperature sensor Climate control unit: terminal voltage (D, M)
GRear window defroster switchRear window defroster relayRear window defroster switch OFFB+Wiring harness: continuity, short circuit (Climate control unit-rear window defroster relay: G-E) Rear window defroster relay
Rear window defroster switch ON0.06Climate control unit: terminal voltage (D, M) Climate control unit
HPassenger compartment temperature sensor inputPassenger compartment temperature sensorCompared with temperature detected by passenger compartment temperature sensorRefer to graph 2 ( see scheme 56)Wiring harness: continuity (Climate control unit-passenger compartment temperature sensor: H-B, C-A) Wiring harness: short circuit (Climate control unit-passenger compartment temperature sensor: H-B) Passenger compartment temperature sensor Climate control unit: terminal voltage (D, M)
IMotor operationAir intake actuatorMoving towards RECIRCULATE10.75Wiring harness: continuity, short circuit (Climate control unit-air intake actuator: I-F, K-D) Air intake actuator
Moving towards FRESH0.72
J+5VAir mix actuator Airflow mode actuator Solar radiation sensorIG SW ON5.11Wiring harness: short circuit (Climate control unit-air mix actuator, airflow mode actuator, Solar radiation sensor: J-A, B, A) Air mix actuator Airflow mode actuator Solar radiation sensor Climate control unit: terminal voltage (D, M)
IG SW OFF0.01Climate control unit replacement
KMotor operationAir intake actuatorMoving towards FRESH10.89Wiring harness: continuity, short circuit (Climate control unit-air intake actuator: K-D, I-F) Air intake actuator
Moving towards RECIRCULATE0.72
LAmbient temperature sensor inputAmbient temperature sensorCompared with temperature detected by ambient temperature sensorRefer to graph 1 ( see scheme 56)Wiring harness: continuity (Climate control unit-ambient temperature sensor: C-A, L-B) Wiring harness: short circuit (Climate control unit-ambient temperature sensor: L-B) Ambient temperature sensor Climate control unit: terminal voltage (D, M)
MIG2A/C 10A fuseIG SW ONB+Wiring harness: continuity, short circuit (Climate control unit-fuse: M-A/C 10 A) A/C 10 A fuse
IG SW OFF1.0 or lessWiring harness: continuity, short circuit (Climate control unit-fuse: M-A/C 10 A)
NPotentiometer inputAir mix actuatorSet temperature at MAX COLD0.72Wiring harness: continuity, short circuit (Climate control unit-air mix actuator: N-C) Air mix actuator Climate control unit: terminal voltage (J)
Set temperature at MAX HOT4.42
OMotor operationAirflow mode actuatorMoving towards VENT10.39Wiring harness: continuity, short circuit (Climate control unit-airflow mode actuator: O-D, Q-F) Airflow mode actuator
Moving towards DEFROSTER0.74
PPotentiometer inputAirflow mode actuatorVENT4.41Wiring harness: continuity, short circuit (Climate control unit-airflow mode actuator: P-C) Airflow mode actuator Climate control unit: terminal voltage (J)
BILEVEL3.54
HEAT2.60
HEAT/DEF1.69
DEFROSTER0.74
QMotor operationAirflow mode actuatorMoving towards DEFROSTER9.98Wiring harness: continuity, short circuit (Climate control unit-airflow mode actuator: Q-F, O-D) Airflow mode actuator
Moving towards VENT0.70
RB+ROOM 15 A fuseUnder any conditionB+Wiring harness: continuity, short circuit (Climate control unit-fuse: R-ROOM 15 A) ROOM 15 A fuse
SMotor operationAir mix actuatorMoving towards HOT10.91Wiring harness: continuity, short circuit (Climate control unit-air mix actuator: S-F, U-D) Air mix actuator
Moving towards COLD0.70
TBlower motor feed backBlower motor Power MOS FETFan stopped11.84Wiring harness: continuity, short circuit (Climate control unit-blower motor: T-A) (Climate control unit-power MOS FET: T-B, V-E) (Blower motor-blower relay: B-A) (Blower relay-fuse: D-BLOWER 40 A) Wiring harness: continuity (Power MOS FET-body ground: A-GND) (Blower relay-ground: A-GND) Power MOS FET Blower motor Blower relay BLOWER 40 A fuse A/C 10 A fuse Power MOS FET replacement
Fan: manual LO7.29
Fan: manual HI0.20
UMotor operationAir mix actuatorMoving towards COLD10.96Wiring harness: continuity, short circuit (Climate control unit-air mix actuator: U-D, S-F) Air mix actuator
Moving towards HOT0.70
VBlower fan speed controlPower MOS FETFan stopped0.07Climate control unit: terminal voltage (T)
Fan: manual LO3.10
Fan: manual HI7.23
WTNS signalTNS relayHeadlight switch OFF1.0 or lessWiring harness: short circuit (Climate control unit-TNS relay: W-C) TNS relay Headlight switch
Headlight switch ONB+Wiring harness: continuity, short circuit (Climate control unit-TNS relay: W-C) TNS relay Headlight switch
XIllumination controlInstrument clusterHeadlight switch ON and panel light control switch at max0.31Wiring harness: continuity (Climate control unit-instrument cluster: X-2H) (Instrument cluster-body ground: 2A-GND) Instrument cluster
Headlight switch ON and panel light control switch at min9.56Wiring harness: short circuit (Climate control unit-instrument cluster: X-2H)

TERMINAL VOLTAGE REFERENCE

Scheme 15

Scheme 15
Scheme 15

CLIMATE CONTROL UNIT INSPECTION [MANUAL AIR CONDITIONER]

  1. Remove the climate control unit. (See «CLIMATE CONTROL UNIT REMOVAL [MANUAL AIR CONDITIONER]»(ref-343768-S28011108282009101500000) .)
  2. Disconnect the air mix wire from the climate control unit
  3. Install the audio unit. (See «AUDIO UNIT REMOVAL/INSTALLATION»(ref-343789-S01824972822009101500000) ).
  4. Connect the climate control unit connector.
  5. Connect the negative (-) lead of the tester to body ground.
  6. Turn the ignition switch to the ON position.
  7. By inserting the positive (+) lead of the tester into each climate control unit terminal, measure the voltage according to the terminal voltage table. If there is any malfunction, inspect the parts under "Inspection item (s)". If the parts under "Inspection item (s)" are found to be normal, replace the climate control unit.

Scheme 16

Scheme 16: Terminal Voltage Table (Reference)
Scheme 16: Terminal Voltage Table (Reference)
TerminalSignal nameConnected toMeasurement conditionVoltage (V)Inspection item (s)
AIllumination controlInstrument clusterHeadlight switch ON and panel light control switch at max0.45Wiring harness: continuity (Climate control unit-instrument cluster: A-2H) (Instrument cluster-body ground: 2A-GND) Instrument cluster
Headlight switch ON and panel light control switch at min9.96Wiring harness: short circuit (Climate control unit-instrument cluster: A-2H)
BTNS signalTNS relayHeadlight switch OFF1.0 or lessWiring harness: short circuit (Climate control unit-TNS relay: B-C) TNS relay Headlight switch
Headlight switch ONB+Wiring harness: continuity, short circuit (Climate control unit-TNS relay: B-C) TNS relay Headlight switch
C
D
E+5VAirflow mode actuatorIG SW ON4.91Wiring harness: short circuit (Climate control unit-airflow mode actuator: E-B) Airflow mode actuator Climate control unit: terminal voltage (R, L)
IG SW OFF1.0 or lessClimate control unit replacement
FFAN ON/OFFAirflow volume control dialAirflow volume control dial ON0.06Wiring harness: (Climate control unit-airflow volume control dial: F-C) Airflow volume control dial
Airflow volume control dial OFF12.18Wiring harness: continuity (Climate control unit-airflow volume control dial: F-C) Climate control unit: terminal voltage (R) Airflow volume control dial
GPotentiometer inputAirflow mode actuatorVENT4.20Wiring harness: continuity, short circuit (Climate control unit-airflow mode actuator: G-C) Airflow mode actuator Climate control unit: terminal voltage (E)
BILEVEL3.34
HEAT2.44
HEAT/DEF1.56
DEFROSTER0.68
HRear window defroster switchRear window defroster relayRear window defroster switch OFFB+Wiring harness: continuity, short circuit (Climate control unit-rear window defroster relay: H-E) Rear window defroster relay
Rear window defroster switch ON0.06Climate control unit: terminal voltage (L, R) Climate control unit
IEvaporator temperature sensor inputEvaporator temperature sensorCompared with temperature detected by evaporator temperature sensorRefer to graph 2. ( see scheme 58)Wiring harness: continuity (Climate control unit-evaporator temperature sensor: I-B, K-A) Wiring harness: short circuit (Climate control unit-evaporator temperature sensor: I-B) Evaporator temperature sensor Climate control unit: terminal voltage (L, R)
JA/CBCMA/C switch ON, airflow volume control dial at 1st0.03Wiring harness: continuity (Climate control unit-BCM: J-3V) BCM
A/C switch OFF5.02Wiring harness: continuity, short circuit (Climate control unit-BCM: J-3V)
KSensor GNDEvaporator temperature sensor Ambient temperature sensor Airflow mode actuatorUnder any condition1.0 or lessClimate control unit: terminal voltage (L)
LGNDBody groundUnder any condition1.0 or lessWiring harness: continuity (Climate control unit-GND: L-GND)
M
N
O
PB+ROOM 15 A fuseUnder any conditionB+Wiring harness: continuity, short circuit (Climate control unit-fuse: P-ROOM 15 A) ROOM 15 A fuse
QMotor operationAirflow mode actuatorMoving towards DEFROSTER10.60Wiring harness: continuity, short circuit (Climate control unit-airflow mode actuator: Q-F, S-D) Airflow mode actuator
Moving towards VENT0.69
RIG2A/C 10A fuseIG SW ONB+Wiring harness: continuity, short circuit (Climate control unit-fuse: R-A/C 10 A) A/C 10 A fuse
IG SW OFF1.0 or lessWiring harness: continuity, short circuit (Climate control unit-fuse: R-A/C 10 A)
SMotor operationAirflow mode actuatorMoving towards VENT10.64Wiring harness: continuity, short circuit (Climate control unit-airflow mode actuator: S-D, Q-F) Airflow mode actuator
Moving towards DEFROSTER0.68
T
U
VMotor operationAir intake actuatorMoving towards RECIRCULATE10.62Wiring harness: continuity, short circuit (Climate control unit-air intake actuator: V-F, X-D) Air intake actuator
Moving towards FRESH0.66
WAmbient temperature sensor inputAmbient temperature sensorCompared with temperature detected by ambient temperature sensorRefer to graph 1. ( see scheme 58)Wiring harness: continuity (Climate control unit-ambient temperature sensor: W-B, K-A) Wiring harness: short circuit (Climate control unit-ambient temperature sensor: W-B) Ambient temperature sensor Climate control unit: terminal voltage (L, R)
XMotor operationAir intake actuatorMoving towards FRESH10.64Wiring harness: continuity, short circuit (Climate control unit-air intake actuator: X-D, V-F) Air intake actuator
Moving towards RECIRCULATE0.67

TERMINAL VOLTAGE REFERENCE

Scheme 17

Scheme 17
Scheme 17

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