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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.