NO.4 NO TEMPERATURE CONTROL WITH CLIMATE CONTROL UNIT [FULL-AUTO AIR CONDITIONER]

id0702c1812400

4
No temperature control with climate control unit
DESCRIPTION
•  Malfunction in A/C unit and/or climate control unit air mix system
POSSIBLE CAUSE
•  Climate control unit power supply/GND circuit malfunction (Steps 2—4)
•  Air mix actuator circuit malfunction (Steps 5—16)
•  Air mix actuator malfunction (Step 17)
•  A/C unit air mix link, air mix crank, air mix rod, malfunction (Step 18)
•  A/C unit air mix door malfunction (Step 19)
•  Heater piping malfunction (Step 20)

•  When performing an asterisked (*) troubleshooting inspection, shake the wiring harness and connectors while performing the inspection to discover whether poor contact points are the cause of any intermittent malfunctions. If there is a problem, inspect to make sure connectors, terminals and wiring harnesses are connected correctly and undamaged.

Diagnostic procedure

STEP

INSPECTION

ACTION
1
INSPECT COOLANT TEMPERATURE
•  Is the coolant sufficiently warmed up?
Yes
Go to the next step.
No
Warm up the engine, then go to Step 21.
2*
INSPECT CLIMATE CONTROL UNIT POWER SUPPLY FUSE FOR B+ SIGNAL
•  Is the climate control unit power supply fuse for B+ signal normal?.
Yes
Go to the next step.
No
Inspect for short to GND in blown fuse circuit.
Repair or replace as necessary.
Install appropriate amperage fuse.
3*
INSPECT TO SEE WHETHER MALFUNCTION (OPEN CIRCUIT) IS IN B+ SIGNAL WIRING HARNESS (BETWEEN FUSE BLOCK AND CLIMATE CONTROL UNIT) OR ELSEWHERE.
•  Disconnect the climate control unit connector.
•  Turn the ignition switch to the ON position.
•  Measure voltage at climate control unit harness-side connector terminal E (B+ signal).
•  Is the voltage approx. 12V?
Yes
Go to the next step.
No
Repair wiring harness between fuse block and climate control unit, then go to Step 21.
4*
INSPECT TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY) WIRING HARNESS (BETWEEN CLIMATE CONTROL UNIT AND GND) OR ELSEWHERE
•  Climate control unit connector disconnected.
•  Verify that continuity between climate control unit harness-side connector terminal B and GND.
•  Is the continuity?
Yes
Go to the next step.
No
Repair wiring harness between climate control unit and GND.
Inspect GND point condition.
Then go to Step 21.
5*
INSPECT TO SEE WHETHER MALFUNCTION IS IN A/C UNIT OR AIR MIX ACTUATOR
•  Turn the ignition switch to the ON position.
•  Measure the voltage at climate control unit terminal M when temperature control dial at MAX HOT and MAX COLD.
•  Is voltage normal?
Yes
Go to Step 17.
No
Go to the next step.
6*
INSPECT TO SEE WHETHER MALFUNCTION IS IN POTENTIOMETER OR ELSEWHERE
•  Turn the ignition switch to the ON position.
•  Measure voltage at climate control unit terminal K when airflow mode change to DEFROSTER and VENT.
•  Is voltage normal?
Yes
Go to Step 9.
No
Go to the next step.
7*
INSPECT TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY OR SHORT TO BATTERY POWER OR GND) IS IN POTENTIOMETER POWER SUPPLY (CLIMATE CONTROL UNIT TERMINAL X) OR ELSEWHERE
•  Turn the ignition switch to the ON position.
•  Measure voltage at climate control unit terminal X.
•  Is voltage approx. 5V?
Yes
Go to the next step.
No
Repair wiring harness between climate control unit terminal X and follows:
•  Air mix actuator terminal E
•  Airflow mode actuator terminal E
Then go to Step 21.
8*
INSPECT TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY OR OPEN) IS IN POTENTIOMETER GND (CLIMATE CONTROL UNIT TERMINAL S) OR ELSEWHERE
•  Measure voltage at climate control unit terminal S.
•  Is the voltage below. 1.0V?
Yes
Go to Step 12.
No
Repair wiring harness between climate control unit terminal S and follows:
•  Air mix actuator terminal G
•  Airflow mode actuator terminal G
Then go to Step 21.
9
INSPECT TO SEE WHETHER MALFUNCTION (SHORT TO POWER) IS IN WIRING HARNESS (AIR MIX POSITION SIGNAL) OR ELSEWHERE
•  Is climate control unit terminal M voltage approx. 12V, at Step 5?
Yes
Repair wiring harness between climate control unit terminal M and air mix actuator terminal F.
Then go to Step 21.
No
Go to the next step.
10*
INSPECT TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY) IS IN WIRING HARNESS (AIR MIX POSITION SIGNAL) OR ELSEWHERE
•  Turn the ignition switch to the LOCK position.
•  Disconnect the climate control and air mix actuator connectors.
•  Verify continuity between climate control unit terminal M and air mix actuator terminal F at harness-side connector.
•  Is there continuity?
Yes
Go to the next step.
No
Repair wiring harness between climate control unit terminal M and air mix actuator terminal F.
Then go to Step 21.
11*
INSPECT TO SEE WHETHER MALFUNCTION (SHORT TO GND) IS IN WIRING HARNESS (AIR MIX POSITION SIGNAL) OR POTENTIOMETER COMMON (POWER SUPPLY OR GND) HARNESS
•  Verify continuity between climate control unit harness-side connector terminal M and GND.
•  Is there continuity?
Yes
Repair wiring harness between climate control unit terminal M and air mix actuator terminal F.
Then go to Step 21.
No
Inspect and repair for open circuit following:
•  Between air mix actuator terminal E and junction point to airflow mode actuator (potentiometer power supply).
•  Between air mix actuator terminal G and junction point to airflow mode actuator (potentiometer GND).
Then go to Step 21.
12*
INSPECT TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY) IS IN AIR MIX ACTUATOR WIRING HARNESS (BETWEEN CLIMATE CONTROL UNIT AND AIR MIX ACTUATOR) OR ELSEWHERE
•  Turn the ignition switch to the ON position.
•  Measure voltage at the following terminals of climate control unit.
―  Terminal J (COLD motor drive signal)
―  Terminal G (HOT motor drive signal)
•  Are voltages okay?
Yes
Go to the next step.
No
Go to Step 14.
13*
INSPECT TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY) IS IN AIR MIX ACTUATOR OR WIRING HARNESS (BETWEEN CLIMATE CONTROL UNIT AND AIR MIX ACTUATOR)
•  Measure voltage at the following terminals of air mix actuator.
―  Terminal B (COLD motor drive signal)
―  Terminal C (HOT motor drive signal)
•  Are voltage s as shown below?
―  COLD motor drive signal: approx. 10V during COLD and approx. 0.5V during HOT
―  HOT motor drive signal: approx. 0.5V during COLD and approx. 10V during HOT
Yes
Go to Step 18.
No
Repair wiring harness between climate control unit and air mix actuator.
Then go to Step 21.
14*
INSPECT TO SEE WHETHER MALFUNCTION IS IN AIR MIX ACTUATOR OR ELSEWHERE
•  Disconnect the air mix actuator connector.
•  Measure voltage at the following terminals of climate control unit.
―  Terminal J (COLD motor drive signal)
―  Terminal G (HOT motor drive signal)
•  Are voltages okay?
Yes
Go to Step 17.
No
Go to the next step.
15*
INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (SHORT TO B+ BETWEEN CLIMATE CONTROL UNIT AND AIR MIX ACTUATOR) OR ELSEWHERE
•  Disconnect the climate control unit connector.
•  Measure voltage at the following terminals of the climate control unit harness-side connector.
―   Terminal J (COLD motor drive signal)
―  Terminal G (HOT motor drive signal)
•  Are voltages approx. 0V?
Yes
Go to the next step.
No
Repair wiring harness between climate control unit and air mix actuator.
Then go to Step 21.
16*
INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (SHORT TO GND BETWEEN CLIMATE CONTROL UNIT AND AIR MIX ACTUATOR) OR ELSEWHERE
•  Turn the ignition switch to the LOCK position.
•  Verify that continuity at the following harness-aide connector terminals between climate control unit and GND.
―  Terminal J (COLD motor drive signal)
―  Terminal G (HOT motor drive signal)
•  Is there continuity?
Yes
Repair wiring harness between climate control unit and air mix actuator.
Then go to Step 21.
No
Go to the next step.
17
INSPECT AIR MIX ACTUATOR
•  Inspect air mix actuator.
•  Is air mix actuator normal?
Yes
Go to the next step.
No
Replace the air mix actuator.
Then go to 21.
(See AIR MIX ACTUATOR REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].)
18
INSPECT AIR MIX LINK
•  Inspect air mix links for each-side.
―  Is grease on link?
―  Are links securely and properly installed?
―  Are links free of obstructions and hindrances?
•  Are above items okay?
Yes
Go to the next step.
No
Apply grease to links.
If any links are damaged. replace malfunctioning part.
Then go to Step 21.
19
INSPECT TO SEE WHETHER MALFUNCTION IS IN CLIMATE CONTROL UNIT OR AIR MIX DOOR ELSEWHERE
•  Inspect A/C unit and each-side air mix door.
―  Is door free of unit and obstruction, and damage?
―  Are doors securely and properly installed?
•  Are above items okay?
Yes
Go to the next step.
No
Remove the obstruction, or install door in proper position.
If any door are cracked, replace them.
Then go to the next step.
20
INSPECT HEATER LINES
•  Inspect heater lines for followings:
―  Is heater piping free if damage and cracks?
―  Are heater piping connections free of engine coolant leakage?
―  Are heater piping installation points on A/C unit free of engine coolant leakage?
•  Are above items okay?
Yes
Replace the climate control unit.
Then go to the next step.
(See CLIMATE CONTROL UNIT REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER].)
No
If heater piping connections is loosed, tighten connections with specified torque.
Repair or replace heater piping.
Then go to the next step.
21
VERIFY THAT MALFUNCTION SYMPTOM OCCURS AFTER REPAIR
•  Does the unit operate in every temperature setting?
Yes
Trouble shooting completed. Explain repairs customer.
No
Recheck malfunction symptoms, then repeat from Step1 if the malfunction recurs.