Chart 5 Improper Temperature Control

Diagnostic Chart:

Electrical Diagram:

CIRCUIT DESCRIPTION

Based on the various temperature sensor inputs and the selected in-car comfort level, the Body Control Module (BCM) determines the required air temperature and delivery mode to achieve and maintain the comfort level regardless of the outside air temperature.

NOTICE: Verify customer complaint as compared to another 1993 Allante prior to attempting diagnosis.

AIR MIX VALVE ADJUSTMENT PROCEDURE

1. Remove glove box to gain access to programmer.

2. Lift up on air mix valve link to release it from programmer arm.

3. Key 'ON', select 90 AUTO on CCP and wait for programmer arm to stop moving.

4. Pull air mix valve to max heat position.

5. With valve at mechanical limit of travel (max heat), snap link back into programmer arm.

6. Visually check air mix valve movement by selecting different temperature settings.

TEST DESCRIPTION

Test numbers refer to circled numbers on the diagnostic chart.

1. Checks to determine that the heater system has sufficient heating capacity.

2. Checks to determine that the refrigerant system has sufficient cooling capacity.

3. Checks to determine if the sunload sensor reacts correctly to a no light condition.

4. Checks to determine if either the sunload sensor or the power CKT 590 is causing the incorrect reading.

5. Checks to determine if the sunload sensor reacts correctly to a high heat or bright condition.

6. Checks to determine if either the sunload sensor, its alignment to the I/P opening or the ground CKT 736 is causing the incorrect reading.

7. Checks to determine if the outside temperature sensor is providing an accurate temperature reading.

8. Checks to determine if the power CKT 735 has high resistance or is shorted to ground causing the incorrect reading.

9. Checks to determine if either the outside temperature sensor or CKT 736 is causing the incorrect reading.

10. Checks to determine if there is component or 'build' condition which is causing the inside air temperature sensor to have the incorrect reading.

11. Checks to determine if the power CKT 734 has high resistance or shorted to ground causing the incorrect reading.

12. Checks to determine if the inside air temperature sensor, its connectors, alignment within housing or the ground CKT 736 is causing the incorrect reading.