NO.5 NO TEMPERATURE CONTROL WITH A/C AMPLIFIER


BHE070301038W07

5

No temperature control with A/C amplifier.

DESCRIPTION

• Temperature does not change with operating temperature control dial.

POSSIBLE CAUSE

• Air mix actuator (+5 V signal) system malfunction (Steps 3-7, 10)
• A/C amplifier (potentiometer GND signal) system malfunction (Steps 8, 9)
• Air mix actuator (potentiometer input signal) system malfunction (Steps 11-13)
• Air mix actuator (potentiometer GND signal, motor drive signal) system malfunction (Step 14)
• Air mix actuator system malfunction (Steps 15, 16)
• A/C unit air mix door malfunction (Steps 17, 18)

• 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, check to make sure connectors, terminals and wiring harnesses are connected correctly and undamaged.

Diagnostic procedure

STEP

INSPECTION

ACTION

1

INSPECT COOLANT TEMPERATURE

• Is coolant sufficiently warmed up?
Yes
Go to next step.
No
Warm engine up, then go to Step 19.
2

CHECK CIRCUITS COMMON TO BOTH AIR MIX ACTUATOR AND AIRFLOW MODE ACTUATOR

• Does airflow mode change when operating airflow mode selector switch?
Yes
Go to Step 10.
No
Go to next step.
3

CHECK TO SEE WHETHER PROBLEM IS IN AIR MIX ACTUATOR +5 V SIGNAL OR POTENTIOMETER GND SIGNAL

• Is air mix actuator set at MAX HOT and airflow mode actuator at VENT?
(Verify position of air mix actuator link and airflow mode actuator link.)
Yes
Go to next step.
No
Go to Step 8. (Set actuator at MAX COLD and DEFROSTER.)
4*

CHECK TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY) IS IN WIRING HARNESS (BETWEEN A/C AMPLIFIER AND AIR MIX ACTUATOR) OR ELSEWHERE

• Turn the ignition switch to ON position.
• Is there voltage of approx. 5 V at A/C amplifier connector (16-pin) terminal 2P (+5 V signal)?
Yes
Repair wiring harness between A/C amplifier and air mix actuator, then go to Step 19.
No
Go to next step.
5*

CHECK TO SEE WHETHER MALFUNCTION IS IN AIR MIX ACTUATOR (SHORT TO GROUND) OR ELSEWHERE

• Disconnect air mix actuator connector.
• Is there voltage of approx. 5 V at A/C amplifier connector (16-pin) terminal 2P (+5 V signal)?
Yes
Inspect air mix actuator, then go to Step 19. (See AIR MIX ACTUATOR INSPECTION.)
No
Go to next step.
6*

CHECK TO SEE WHETHER MALFUNCTION IS IN AIRFLOW MODE ACTUATOR (SHORT TO GROUND) OR ELSEWHERE

• Disconnect airflow actuator connector.
• Is there voltage of approx. 5 V at A/C amplifier connector (16-pin) terminal 2P (+5 V signal)?
Yes
Inspect airflow mode actuator, then go to Step 19. (See AIRFLOW MODE ACTUATOR INSPECTION.)
No
Go to next step.
7*

CHECK TO SEE WHETHER MALFUNCTION (SHORT TO GROUND) IS IN A/C AMPLIFIER OR WIRING HARNESS (BETWEEN A/C AMPLIFIER AND AIR MIX ACTUATOR)

• Disconnect A/C amplifier connector (16-pin).
• Is there continuity between A/C amplifier connector (16-pin) terminal 2P (+5 V signal) and body ground?
Yes
Repair wiring harness between A/C amplifier and air mix actuator, then go to Step 19.
No
Replace A/C amplifier, then go to Step 19.
8*

CHECK TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY) IS IN A/C AMPLIFIER OR WIRING HARNESS (BETWEEN A/C AMPLIFIER AND AIR MIX ACTUATOR)

• Disconnect A/C amplifier connector (16-pin) and air mix actuator connector.
• Is there continuity between A/C amplifier connector (16-pin) terminal 2O (potentiometer GND signal) and air mix actuator connector terminal C (L.H.D.) or A (R.H.D.)?
Yes
Go to next step.
No
Repair wiring harness between A/C amplifier and air mix actuator, then go to Step 19.
9*

CHECK TO SEE WHETHER MALFUNCTION (SHORT TO B+) IS IN A/C AMPLIFIER OR WIRING HARNESS (BETWEEN A/C AMPLIFIER AND AIR MIX ACTUATOR)

• Turn the ignition switch to ON position.
• Test voltage at A/C amplifier connector (16-pin) and terminal 2O (potentiometer GND signal).
• Is voltage approx. 12 V?
Yes
Repair wiring harness between A/C amplifier and air mix actuator, then go to Step 19.
No
Replace A/C amplifier, then go to Step 19.
10*

CHECK TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY) IS IN WIRING HARNESS (BETWEEN A/C AMPLIFIER AND AIR MIX ACTUATOR) OR ELSEWHERE

• Turn the ignition switch to ON position.
• Test voltage at air mix actuator connector terminal A (L.H.D.) or C (R.H.D.) (+5 V signal).
• Is voltage approx. 5 V?
Yes
Go to next step.
No
Repair wiring harness between A/C amplifier and air mix actuator, then go to Step 19.
11*

CHECK TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY) IS IN WIRING HARNESS (BETWEEN A/C AMPLIFIER AND AIR MIX ACTUATOR) OR ELSEWHERE

• Turn the ignition switch to LOCK position.
• Disconnect A/C amplifier connector (16-pin) and air mix actuator connector.
• Is there continuity between A/C amplifier connector (16-pin) terminal 2H (potentiometer input signal) and air mix actuator connector terminal E?
Yes
Go to next step.
No
Repair wiring harness between A/C amplifier and air mix actuator, then go to Step 19.
12*

CHECK TO SEE WHETHER MALFUNCTION (SHORT TO GROUND) IS IN WIRING HARNESS (BETWEEN A/C AMPLIFIER AND AIR MIX ACTUATOR) OR ELSEWHERE

• Is there continuity between A/C amplifier connector (16-pin) terminal 2H (potentiometer input signal) and ground?
Yes
Repair wiring harness between A/C amplifier and air mix actuator, then go to Step 19.
No
Go to next step.
13*

CHECK TO SEE WHETHER MALFUNCTION (SHORT TO B+) IS IN WIRING HARNESS (BETWEEN A/C AMPLIFIER AND AIR MIX ACTUATOR) OR ELSEWHERE

• Turn the ignition switch to ON position.
• Test voltage at A/C amplifier connector (16-pin) terminal 2H (potentiometer input signal).
• Is voltage approx. 12 V?
Yes
Repair wiring harness between A/C amplifier and air mix actuator, then go to Step 19.
No
Go to next step.
14*

CHECK TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY) IS IN WIRING HARNESS (BETWEEN A/C AMPLIFIER AND AIR MIX ACTUATOR) OR ELSEWHERE

• Turn the ignition switch to LOCK position.
• Is there continuity between following A/C amplifier connector (16-PIN, 24-pin) terminals and air mix actuator connector terminals?
– Terminal 2O and terminal C (L.H.D.) or A (R.H.D.) (potentiometer GND signal)
– Terminal 1V and terminal G (L.H.D.) or F (R.H.D.) (motor drive signal)
– Terminal 1U and terminal F (L.H.D.) or G (R.H.D.) (motor drive signal)
Yes
Go to next step.
No
Repair wiring harness between A/C amplifier and air mix actuator, then go to Step 19.
15

INSPECT A/C UNIT AIR MIX ACTUATOR LINK AND CRANK

• Is there grease on the link and crank?
Yes
Go to next step.
No
Apply grease, then go to Step 19.
16

INSPECT AIR MIX ACTUATOR

• Inspect air mix actuator.
• Is it normal?
Yes
Go to next step.
No
Replace air mix actuator, then go to Step 19. (See AIR MIX ACTUATOR REMOVAL/INSTALLATION.)
17

VERIFY THAT A/C UNIT AIR MIX DOORS DO NOT HAVE ANY FOREIGN MATERIAL OR OBSTRUCTION

• Is there any foreign material or obstructions on any A/C unit door?
Yes
Remove material/obstruction, then go to Step 19.
No
Go to next step.
18

INSPECT A/C UNIT AIR MIX DOORS

• Are all doors within A/C unit securely and properly positioned?
• Inspect A/C unit doors.
– Are doors cranked or damaged?
– Are doors securely and properly installed?
• Are they normal?
Yes
Replace A/C amplifier, then go to next step.
(Malfunction in A/C amplifier temperature control lever circuit)
No
Replace or install door(s) in proper position, then go to next step.
19

CONFIRM THAT MALFUNCTION SYMPTOMS DO NOT RECUR AFTER REPAIR

• Does temperature change when operating temperature control dial?
Yes
Troubleshooting completed.
Explain repairs to customer.
No
Recheck malfunction symptoms, then repeat from Step 1 if malfunction recurs.