A/C Control Assembly - Service Parts

REF: HEATING & AIR CONDITIONING

NO.: AC004-96

DATE: JULY 19, 1996

MODEL: SC 300/400

TITLE:
1992 - 1995 SC 300/400 A/C CONTROL ASSEMBLY SERVICE PARTS

To allow repairs to the A/C Control Assembly, service parts are now available. The following information on parts and troubleshooting will aid you in addressing complaints with the LCD display, night illumination or switch indicators.





PREVIOUSLY AVAILABLE PARTS:





CURRENTLY AVAILABLE PARTS:

* Face Plate is not available as a separate part.

TROUBLE SHOOTING:





Use the matrix chart as a guide to repairs. Verify necessary inputs to the A/C Control Assembly from the vehicle prior to disassembly. Use the repair manual, A/C system section, to validate such as B+, ILL+, ground, etc..

NOTE:
If symptoms still exist after the suspect areas have been tested and found not to be faulty, replace the amplifier.

[1] LCD illumination bulbs are not serviceable, Control Switch must be replaced if illumination does not occur.

AIR CONDITIONING CONTROL DISASSEMBLY:





1. Remove Air Conditioning Control Assembly.

2. Separate Control Panel from case.





a. Cut the cloth tape on both sides of the case (See Fig. 2).





b. Remove 2 screws and release the 6 clips to separate the Control Panel from the case.





c. Disconnect 2 connectors to separate the Control Panel from the case.





d. Remove the wire harness (See Fig. 5).

3. Remove Control Switch.





a. To replace the Control Switch remove 2 screws and release 4 clips (See Fig. 6).





b. Separate Control Switch from face plate.

4. Replace the Night Illumination Bulb.





Using a flat-bladed screwdriver, remove and replace the Night Illumination Bulb.

INSPECTION PROCEDURE:





1. Bulb Circuit:

^ Bulb Inspection - Perform the following test on suspect Night Illumination Bulbs. Check for continuity as shown. Replace the bulb if there is no continuity.

^ Bulb Circuit Inspection - Verify continuity between terminals 22 and 24. If there is no continuity, replace Control Switch.

2. Switch Circuit:





^ Switch Continuity Inspection - Check that there is continuity between the terminals while the switch is pressed.





^ If there is no continuity between even one pair of terminals, replace the Control Switch.





3. Indicator Lamp Circuit:

^ Connect two 1.5 v dry cell batteries in series. Using the table, check that each suspect indicator lamp illuminates.

NOTE:
Since the indicator lamps are LEDs, do not mix the "+" and terminals of the test batteries or apply power to them for more than 3 seconds at a time.





^ If a suspect LED does not illuminate when tested, replace the Control Switch.





PART NUMBER INFORMATION:





WARRANTY INFORMATION:

* Listed time for sub-operations are to be added to base operation to R&R the A/C Control Assembly and include all necessary checks and tests.

** As applicable per the Lexus Universal Flat Rate Manual.