SERVICE MAN. UPDATE SEC. 8A-68 A/C AIR DELIVERY TEMP. CONTROL
SUBJECT: SERVICE MANUAL UPDATE - SECTION 8A-68 A/C C68 AIR DELIVERY - TEMPERATURE CONTROLS (CODES/DIAGNOSTIC TEXT)
VEHICLES AFFECTED: 1989-90 OLDS 'W
The trouble codes and diagnostic text found in Section 8A-68 is incorrect. Please make a reference to this Bulletin in your copies of the 1989 and 1990 Cutlass Supreme Service Manuals.
AIR DELIVERY AND TEMPERATURE CONTROLS
ON-BOARD DIAGNOSTIC MODE
The C68 air conditioning is equipped with an on-board diagnostic feature which allows the Heater and A/C Control Assembly to detect certain system faults. The diagnostic feature can also be used to display certain data paramenters. If the Heater and A/C Control Assembly detects a fault in the system, the C degrees or F degrees annunciator will flash during the first two minutes of vehicle operation
Entry into the diagnostic mode is gained by depressing the OUTS TEMP and BI- LEVEL buttons at the same time. Once the diagnostic mode is entered, any trouble codes stored will be displayed. If none are present. 00 will be displayed.
If the WARM button is depressed after the trouble codes have been displayed, the data mode will be entered. The information available in the data mode is displayed in units used by the computer which may not be of use in observing the system. To exit the diagnostic mode, press any mode button.
A list of the Trouble Codes and their meanings follows:
TROUBLE CODE DESCRIPTION ------------ ---------------- 00 No System Faults
01 or 101 In-Car Temperature Sensor Short
02 or 102 In-Car Temperature Sensor Open
03 or 103 Outside Temperature Sensor Short
04 or 104 Outside Temperature Sensor Open
05 or 105 Air temperature Door Feedback Circuit
09 or 109 Serial Data line Failure
NOTE: A two digit trouble code indicates the fault is present now. A three digit trouble code indicates an intermittent fault.
CLEARING CODES
To clear codes from the Heater and A/C Control Assembly, remove ELEC FUSE 2.
TROUBLE SHOOTING HINTS
- Try the following checks before doing the System Check
1. Check the CLUST Fuse 9by checking if the Speedometer works properly.
2. Check ELEC FUSE 2 by checking if the Radio operates properly
3. If the Steering Wheel Controls do not operate the Radio or the Heater and A/C controls, refer to Radio cell 150 for diagnosis.
4. If Heater and A/C control does not switch from English to metric, refer to diagnosis in the Instrument Panel Cluster diagnosis.
- Go to the A/C system checks in 8A-62 for a guide to normal operation. Refer to the system diagnosis if other results occur.
SYSTEM DIAGNOSIS
- Do the Diagnostic Test(s) listed next to your symptom in the Symptom Table. Code Symptoms must be diagnosed first.
SYMPTOM TABLE
SYMPTOM 00 TEST --------------- ---------------------------------- Code 01 or 02 is TEST A: In-car Temperature Sensor Test set
Code 03 or 04 TEST B: Outside Temperature Sensor Test is set
Code 05 is set TEST C: Air Temperature Door Motor Test
Code 09 is set TEST D: Serial Data Line Test
Steering Wheel Control Refer to diagnosis in Radio Cell 150 functions do not operate the heater and A/C controls Assembly functions properly
Code 02 and 04 are set Check YEL(61) wire for an open between splice S258 and Heater and A/C Control Assembly. If YEL (61) wire is OK, replace Heater and A/C Control Assembly
Temperature of air TEST C: Air Temperature Door Motor Test discharged from vents is either too cold or hot
Heater and A/C TEST E: Heater and A/C Control Assembly Control Assembly Voltage Test display is blank
Air is not discharged TEST F: Solenoid Box Test from the correct duct.
TEST A: IN-CAR TEMPERATURE SENSOR TEST (TABLE 1) --------------------------------------------------- Measure: VOLTAGE At: IN-CAR TEMPERATURE SENSOR CONNECTOR (Disconnected)
Condition:
- Ignition: RUN
Measure Correct For Between Voltage Diagnosis --------- ------- --------- B (DK GRN) 5 volts See 1 & Ground
B (DK GRN) 5 volts See 2 & A (YEL)
- If all voltages are correct, replace In-car Temperature Sensor.
1. If Code 01 was set, check for a short to ground in the DK GRN (734) wire. If Code 02 was set, check for an open in the DK GRN (734) wire. If wire is OK, replace Heater and A/C Control Assembly.
2. Check/repair YEL (61) wire for an open.
TEST B: OUTSIDE TEMPERATURE SENSOR TEST (TABLE 1) --------------------------------------------------- Measure: VOLTAGE
At: OUTSIDE TEMPERATURE SENSOR CONNECTOR (Disconnected)
Condition:
- Ignition: RUN
Measure Correct For Between Voltage Diagnosis ------- ------- ---------- B (GRN/ BLK) & 5 volts See 1 Ground
B (GRN/ BLK) & A 5 volts See 2 (YEL)
- If all voltages are correct, replace In-car Temperature Sensor.
1. If Code 03 was set, check for a short to ground in the LT GRN/BLK (735) wire. If Code 04 was set, check for an open in LT GRN/BLK (735) wire. If wire is OK, replace Heater and A/C Control Assembly.
2. Check/repair YEL (61) wire for an open.
TEST C: AIR TEMPERATURE DOOR MOTOR TEST (TABLE 1) ------------------------------------------------- Measure: VOLTAGE
At: AIR TEMPERATURE DOOR MOTOR CONNECTOR (Disconnected)
Conditions:
- Ignition: RUN - A/C Mode: AUTO - Outside Temperature: Above 60 F (16 C)
Measure Correct For Between Voltage Diagnosis ------- -------- ---------- 10 (PNK/ BLK) & Battery See 1 Ground
10 (PNK/ BLK) & 7 Battery See 2 (BLK)
10 (PNK/ BLK) & 9 Battery See 3 (PPL/WHT)
- If all voltages are correct, go to Table 2.
1. Check/repair PNK/BLK (750) wire for an open.
2. Check/repair BLK (150) wire for an open.
3. Check PPL/WHT (930) wire for an open.
If PPL/WHT wire is OK, replace the Heater and A/C Control Assembly.
AIR DELIVERY AND TEMPERATURE CONTROLS
TEST C: AIR TEMPERATURE DOOR MOTOR TEST (TABLE 2) ------------------------------------------------- Measure: VOLTAGE
At: AIR TEMPERATURE DOOR MOTOR CONNECTOR (Connected)
Condition:
- Ignition: RUN
Measure Correct For Between Voltage Diagnosis ------- -------- ---------- 10 (PNK/ Between .5 BLK) & 9 volts and See 1 (PPL/WHT) Battery
9 (PPL/ Between .5 WHT) & 7 volts and See 2 (BLK) Battery
Conditions:
- A/C Mode: Auto
- Outside Temperature: Above 60 F (16 C); measure while alternately pressing the warm and cool buttons.
Voltage levels 8(LT BLU/ change as BLK) & buttons are See 3 Ground pressed
-If voltage level changes as warm and cool buttons are pressed, check Air Temperature Door Linkage. If Linkage is OK, replace Air Temperature Door Motor.
1. Check the PPL/WHT (930) wire for an open. If wire is OK, replace Heater and A/C Control Assembly.
2. Check the PPL/WHT (930) wire for a short to ground. If wire is OK, replace the Air Temperature Door Motor.
3. Check LT BLU/BLK (733) wire for an open to ground. If LT BLU/BLK wire is OK, replace Heater and A/C Control Assembly.
TEST D: SERIAL DATA LINE TEST (Table 1) ---------------------------------------- Measure: RESISTANCE
At: HEATER AND A/C CONTROL ASSEMBLY CONNECTOR C3 (Disconnected)
Conditions:
- Electronic Control Module Connector disconnected.
- Connect a fused jumper between ECM connector terminal B5 and ground.
Measure Correct For Between Result Diagnosis -------- --------- ---------- C3/9 (ORN) 0 ohms See 1 & Ground
- Remove fused jumper.
C3/9 (ORN) Infinite ohms See 2 & Ground
- If all measurements are correct, go to Table 2.
1. Check/repair ORN (4 6 1) wire for an open.
2. Check ORN (461) wire for a short to ground. If ORN (46 1) wire is good, refer to Data Line cell 51 for further diagnosis.
TEST D: SERIAL DATA LINE TEST (Table 2) ---------------------------------------- Measure: VOLTAGE At: HEATER AND A/C CONTROL ASSEMBLY CONNECTOR C3 (Disconnected)
Conditions:
- Ignition: RUN - Reconnect Electronic Control Module from previous step.
Measure Correct For Between Voltage Diagnosis
C3/9 (ORN) Approximately See 1 & Ground 5 volts
- If voltage is correct, replace Heater and A/C Control Assembly after checking for good terminal contact.
1. Replace Electronic Control Module (ECM) after checking for good terminal contact.
AIR DELIVERY AND TEMPERATURE CONTROLS
TEST E: HEATER AND A/C CONTROL ASSEMBLY VOLTAGE TEST ----------------------------------------------------
Measure: VOLTAGE
At: HEATER AND A/C CONTROL ASSEMBLY CONNECTOR C1 AND C3 (Disconnected)
Conditions:
- Ignition: RUN
Measure Correct For Between Voltage Diagnosis --------- ------- ---------- C3/8 (ORN) Battery See 1 & Ground
C3/8 (ORN) & C3/7 Battery See 2 (BLK/WHT)
C3/12 (PNK/ BLK) & Battery See 3 Ground
C3/12 (PNK/ BLK) & Battery See 4 C1/14 (BLK)
- If all voltages are correct, replace Heater and A/C Control Assembly after checking for good terminal contact.
1. Check/repair ELEC Fuse 2 and ORN (640) wire.
2. Check/repair BLK/WHT (15 1) wire for an open.
3. Check/repair CLUST Fuse 10 and PNK/ BLK (750) wire.
4. Check/repair BLK (150) wire for an open.
TEST F: SOLENOID BOX TEST (Table 1) ----------------------------------- Measure: VOLTAGE
At: SOLENOID BOX
Conditions:
- Ignition: RUN
Measure Correct For Between Voltage Diagnosis --------- ------- --------- 6 (PNK/ WHT) & Battery See 1 Ground
- If voltage is correct, go to Table 2.
1. Check/repair A/C Fuse 1 and PNK/WHT (350) wire.
TEST F: SOLENOID BOX TEST (TABLE 2) ------------------------------------ 1. Use the table to check for proper operation of the Heater and A/C Control Assembly solenoid controls. To use the matrix, connect a voltmeter to terminal 6 of the Solenoid Box and to the terminal indicated in the table. Battery voltage should be measured at the terminals indicated with a dot.
Measure: VOLTAGE
At: Disconnected Solenoid Box Connector terminal 6 and terminal indicated in chart
Conditions:
- Ignition: RUN
NOTE: X Indicates battery voltage should be measured
| TERMINAL | TERMINAL| TERMINAL | TERMINAL | TERMINAL | 1 | 2 | 3 | 4 | 5 MODE | DEFROST | HEATER | BI-LEVEL | RECIRC | A/C | SOLENOID | SOLENOID | SOLENOID | SOLENOID | SOLENOID -----------------|-----------|------------|------------|--------------- OFF | X | | | -----------------|-----------|------------|------------|--------------- HEAT | X | | | -----------------|-----------|------------|------------|--------------- LOWER | X | X | | X -----------------|-----------|------------|------------|--------------- A/C | | | | MAX | X | X | X | X -----------------|-----------|------------|------------|--------------- DE- | | | | FROST X | | | | -----------------|-----------|------------|------------|--------------- B1-LEVEL | | X | | -----------------|-----------|------------|------------|--------------- UPPER | | | | DEFOG | X | X | | X -----------------|-----------|------------|------------|---------------
- If a measurement is not correct, check the Wire between the Solenoid Box and the Heater and A/C Control Assembly for a open or short to ground. If the wire is good, replace the Heater and A/C Control Assembly,
AIR DELIVERY AND TEMPERATURE CONTROLS
If all measurements are correct but air is not discharged through the correct duct, check for a good vacuum source and check all vacuum hoses for any leaks, kinks or restrictions. If all vacuum lines are good, replace the Solenoid Box.
CIRCUIT OPERATION
The air doors that control the flow of air through the A/C Module are operated by vacuum actuators. Solenoid valves located in the Solenoid Box apply or vent vacuum to the actuators. The solenoids are controlled by solid state circuits in the Heater and A/C Control Assembly. Pushbutton switches in the Heater and A/C Control Assembly determine the A/C Operating Mode. Depending on the mode selected, the Control Assembly will determine which air doors should be operated.
Two Temperature Sensors are used by the Heater and A/C Control Assembly. Both are of the negative temperature coefficient type. Their resistance decreases with temperature increases. The In-car Sensor indicates the inside air temperature and the Outside Temperature Sensor indicates the outside air temperature. The difference between the two sensor indications is used by the control circuits to determine whether the incoming air should be cooled or warmed, and to what degree, in order to bring the in-car temperature to the selected temperature as quickly as possible. If a malfunction should occur in either the In-car or Outside Temperature Sensor circuits, the Heater and A/C Control Assembly will set a trouble code. It will also substitute a temperature value of 75 F (24 C) if the In-car Sensor circuit is at fault or 49 F (9 C) if the Outside Temperature Sensor circuit is at fault. The substitute temperature values will allow the system to continue operations.
RECIRCULATION DOOR
The Recirculation Door is closed in most of the operating modes permitting outside air to enter the A/C Module. It is opened only in the A/C Modes and at a Temperature Setting of 65 F. When open, air from inside the car is recirculated to get maximum cooling.
AIR TEMPERATURE DOOR
The Air Temperature Door is positioned by the Air Door Motor. When the door is in the COOL position, air is prevented from passing through the Heater Core. The A/C Module then provides maximum cooling. The door can be placed by the motor in any position between COOL and WARM and will provide any degree of warming the air after it has passed through the A/C Evaporator Core.
HEATER DEFROST DOOR
The Heater Defrost Door can be moved to any one of three positions. The Heater Defrost Door actuator consists of two vacuum chambers operated by two vacuum actuators. When the A/C System is operated in the Bi-Level or the Defog mode, neither vacuum chamber is evacuated and the door is in the mid position. Air flow is then directed to the defrost outlets and the Heater Outlets. If the Heater Vacuum actuator is operated, the actuator moves the door to position C, which directs air flow to the heater outlets (Lower Mode). If the Defrost Vacuum actuator is operated, the door moves to position A which directs air flow to the Defrost Outlets. This is the position the door is in when operating Defrost mode.
BI-LEVEL DOOR
The Bi-Level Door is in position B when the air conditioning is activated, or when the Bi-Level or upper modes are selected. In this position air flow is directed out of the A/C outlets. If Lower, Defrost or Defog mode is selected the Bi- Level Solenoid is deenergized. This will vent the vacuum from the Bi-Level Door Vacuum Actuator allowing the door to move to position A. The air flow will now be directed toward the heater and defrost outlets.
A/C DOOR -------- The purpose of the A/C Door is to divert air conditioned air through the A/C outlets and prevent air flow through the heater and defrost outlets. The A/C Door is in position B when the system is in the maximum A/C or normal A/C modes. The A/C door is in position 'A' in all other modes.
DELAY MODE
The delay mode is used to prevent the car occupant's breath from fogging the windshield when the outside temperature is low and the engine is cold. The Heater and A/C Control Assembly will set the doors so that air flow is directed to the windshield with low blower operation. The system will stay in the delay mode until engine coolant temperature reaches 49 C (120 F) or after four minutes, whichever comes first. The system will then operate normally in the selected mode.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
