A/c-Heater System - Automatic Buick Electra VI

DESCRIPTION

The Electronic Touch Climate Control (ETCC) system automatically regulates and maintains operator-selected in-vehicle temperatures from maximum "COOL" of 65°F (15.6°C), to maximum "HEAT" of 85°F (32°C) regardless of changes in outside air temperature.

Particularly during humid weather, to increase passenger comfort and limit window fogging, the ETCC system removes excess moisture from the air when the A/C compressor is engaged and operating. The ETCC automatically regulates fan speed, air inlet positions and air outlet positions.

Each control panel has many functions. Basically, between models, there are 3 different control panels used. The control panel used on Electra and LeSabre sedans has a digital temperature display, and can also diagnose itself using trouble codes. This panel has 14 different key pads each with a different function. (Scheme 2)

The control panel used on Electra and LeSabre wagons and all Regal models has a bar graph temperature selector with LED annunciators for each temperature selection. This control panel has 11 different key pads each with a different function. (Scheme 1)

The control panel used on Skyhawk models uses the same type of bar graph temperature control selector as the Electra and LeSabre wagons and all Regal models. Yet, in this instance, the faceplate only contains 9 different key pads.

Some major differences between these and older automatic climate control systems are: State of the art digital microprocessor with programmable memory, hidden switch for self-diagnosis (Electra and LeSabre sedans only), individual in-car and outside air temperature sensors, digital vacuum fluorescent display (Electra And LeSabre sedans only), English to metric conversion capability (Electra and LeSabre sedans only), and an optional rear window defogger key pad switch.

Individual electric, motor-driven mode valve actuators with position feedback circuits are used to position the A/C mode valves on Electra and LeSabre wagons. Whereas, on all other models, these same airflow control valves are controlled by a programmer and solenoid-controlled, vacuum-operated actuators.

Feedback is provided by a fixed resistor at each actuator control arm position. Automatic operation of the system depends on 3 factors: 1) information from outside air and in-car temperature sensors, 2) what settings have been selected, and 3) the position of the temperature door.

The system also automatically compensates for warmer or cooler outside temperatures as well as any heat generated by sunlight entering the windows.

OPERATION

The central control of the system is accomplished through the A/C control head panel microprocessor. On the front of the control head panel are a series of low current switches. When touched, they transfer the control selection to a microprocessor inside the control panel.

The microprocessor serves 2 functions. It executes desired selection through power transistors and remembers and displays the last selection ordered through light emitting diodes (LEDs) in the faceplate when ignition is turned on.

The A/C controller is programmed to provide a specific air outlet mode and blower motor speed for each temperature valve position.

To operate these systems, first select the desired mode function such as "HEAT" or "ECON". Then select a desired temperature and fan speed. The system will then operate within these parameters to bring about the desired comfort range.

The system can also be put totally into automatic by selecting the "AUTO" mode. In this mode, after a desired temperature has been selected, the entire system will operate automatically, changing from heat to A/C as the need arises to keep the vehicle interior at the desired comfort range.

Scheme 1

Scheme 2

CONTROL HEAD

Note. The control head and programmer are not serviceable. If for any reason they must be replaced, an exchange unit must be obtained from an A/C Delco Service Center.

The control head used on Electra and LeSabre wagons, and all Regal and Skyhawk models is housed in a plastic box mounted to the instrument panel. The control head faceplate contains A/C mode control, blower fan control and temperature guide setting switches.

These low current switches transfer the control selections to the microprocessor which serves three functions. They execute the selection through power transistors, remember the last temperature and blower selection ordered, and display (via LED annunciators) that previously made temperature and blower selection the next time the ignition is turned on.

In-car temperatures are controlled in all mode positions: "HEAT", "ECON", "AUTO", "BI-LEV" and "DEF". A timer delays blower operation for approximately 3 minutes after the ignition is turned on and the control head has been set to either "HEAT" or "BI-LEV" modes. Yet, the blower fan will start immediately in the "DEFROST" and "A/C" modes.

The control head on Electra and LeSabre sedans consists of 3 electronic printed circuit boards, housed in a plastic box attached to the instrument panel. Two circuit boards, the main central processing board and the digital display, connect to the controllers faceplate. There are 14 soft touch key pad switches on the flat surface membrane faceplate. Each of these address the microprocessor. The microprocessor has both Random Access Memory (RAM) and Read Only Memory (ROM).

The RAM memory stores such information as the present operating mode, position of each valve opening within the A/C module, calculations made by the arithmetic logic unit and the current in-car and outside air temperatures. The ROM retains in memory the last mode settings selected before the vehicles ignition was last turned off.

On all models except Skyhawk, 3 connector bodies attach to the rear of the control head.

Electra & LeSabre Wagons

The 22-wire connector provides power feedback circuits to the electric actuator motors. The 6-wire connector supplies B+ (battery feed) power, ignition switch power, in-car sensor circuit power, and backlighting power to the faceplate.

The 8-wire connector supplies power to all A/C components in the engine compartment, such as blower motor, compressor and blower motor control unit.

Electra & LeSabre Sedans

The 24-wire connector provides power and feedback circuits to the A/C control head.

Regal

A 22-wire connector supplies power and feedback circuits to 5 vacuum solenoids in the programmer and to an electric temperature door actuator.

The 6-wire connector supplies B+ (battery feed) power, ignition switch power, in-car sensor circuit power and backlighting power to the faceplate.

The 8-wire connector supplies power to all A/C components in the engine compartment, such as blower motor, compressor and blower motor control unit.

Skyhawk

The 22-wire connector supplies power and feedback circuits to 4 vacuum solenoids in the programmer and to the electric temperature door actuator. It also supplies power to all A/C components in the engine compartment.

The 6-wire connector supplies B+ (battery feed) power, ignition switch power, in-car sensor circuit power and backlighting power to the faceplate. There is no 8-wire connector on Skyhawk models.

Temperature Guide Modes

The various temperature LEDs on the top bar of Electra and LeSabre wagons and all Regal and Skyhawk control head panels should be used only as guides to select a particular temperature setting, regardless of outside ambient temperature.

Control head guide settings are spaced out between 65°F (18°C) and 85°F (29°C) with 1° increments. Electra and LeSabre sedans use a digital fluorescent display. To change temperature on all models, push the "WARMER" or "COOLER" switch until the LED under the desired degree setting lights up.

When the "65°" selection is made, automatic adjustment is locked out and the system operates at full cooling capacity. The blower fan will operate on high speed and the recirculation door will be closed. Temperatures will drop well below 65°F (18.3°C). This will continue until some other selection is made.

The reverse is also true when the "85°" selection is made. The system will operate at full heating and will exceed 85°F (29°C). This will continue until some other selection is made.

"OFF" Mode

With this mode selected, the system will not let the fan blower motor or A/C compressor run. However, the system will still try to reach the selected temperature range even though there is no forced air or A/C function. This position also forces the recirculation door open to outside air and forces all air coming out of the module to the floor.

"HEAT" Mode

In this mode, the system will not let the A/C compressor run. It will adjust to the guide temperature range that has been selected. Yet, it cannot cool the vehicle colder than the outside ambient temperature. All incoming air is from outside. The only automatic operation in this mode is regulating the temperature door position and fan speed. If the engine is cold, blower operation will be delayed.

"ECONOMY" Mode

In this mode, the A/C compressor will not run. The system will try to adjust to the guide temperature range that has been selected. However, it cannot cool the vehicle colder than outside ambient temperatures. This mode is automatic and determines fan blower speed and air outlet positions from various inputs. All incoming air into the module is from outside.

"AUTO" Mode

In this mode everything is controlled automatically by various inputs. The system will adjust to guide temperature range selected and stay there, maintaining the temperature with least possible noise level. This mode also has the capability of any fan blower speed, any air inlet position, and any air outlet position required to reach and maintain selected guide temperature range.

"BI-LEVEL" Mode

In this mode, the system will let air enter the vehicle only through the bi-level heater and A/C outlets. This mode is automatic in that it can bring the vehicle to the guide temperature range selected, and control fan blower speed and air inlet by interpreting various input signals. This mode is also good for defogging side windows.

"DEF" Mode

In this mode the system will run the fan blower at a fixed high rate of speed, (unless a fan override button is selected after initial start up) and air will exit out the defroster openings.

System is automatic in this setting as the A/C compressor and air inlet are controlled automatically based on various input signals. This is the only mode in automatic operation where there will be no blower delay when heat is called for.

The 8-bit microprocessor is essentially the entire central processing unit (CPU) of the climate control system, and is contained on a single chip. The elements on such a chip are not wired together, but are layered as a unit during the manufacturing process. The microprocessor also has a self-diagnosis system for detecting faults in the A/C system.

SENSORS

An in-car sensor and an outside (ambient) temperature sensor are used to provide basic control inputs for the system. Both are of the thermistor type and develop a low voltage signal which is directly proportional to actual temperature readings.

The in-car sensor is mounted in the instrument panel carrier and is clamped to the programmer sensor duct. The ambient outside air sensor is located on the cowl in a notch under the hood lace on the left side of the engine compartment. These sensors provide the basic control inputs for the system's automatic function. (Scheme 21)

ASPIRATOR

The aspirator is mounted on the A/C-heater module. A small amount of air from cold air portion of A/C-heater module is drawn through a hose creating a small vacuum. This vacuum causes passenger compartment air to be drawn across the in-car sensor. This sensor then signals the control panel to adjust the temperature as necessary to maintain the preselected comfort range. (Scheme 21)

TEMPERATURE DOOR ACTUATOR

Note. Temperature door actuators are not interchangeable between models.

The temperature door actuator is used to mix hot and cold air in maintaining the desired guide temperature setting. A reversible electric drive motor and feedback variable resistor position the temperature door as selected on the control head panel. The drive motor is connected by a link arm to the temperature door. This allows the door to move clockwise or counterclockwise.

The resistor informs the control head panel of the door's position by varying electrical resistance readings. The actuator is mounted in the center of the A/C module in the passenger compartment.

If improper door operation occurs (binding, obstruction or misadjustment), the actuator shuts off current to drive motor, and causes faceplate LEDs to flash. Internal actuator components are not serviceable. (Scheme 3)

Scheme 3

MODE ACTUATORS & HEATER CONTROL VALVE

On Electra and LeSabre wagons, mode actuators contain an electric drive motor and feedback circuitry.

Doors may be stopped at specific positions as selected by the control head. Non-reversible actuators rotate through 360°. In case of a faulty feedback circuit, the actuator will run continuously until shut off after 20-30 seconds by the control head timer. The mode LEDs on control panel will then flash to indicate malfunction.

Regal and Skyhawk models have 4 vacuum-operated mode actuators. Regal models also use a vacuum heater control valve, while Electra, LeSabre and Skyhawk models have no heater control valve. The air inlet (recirc) door, heater control valve and upper mode door use 2-position actuators.

Lower mode door uses a 3-position actuator with 2 vacuum hoses (one on each side of the diaphragm). These vacuum operated actuators are controlled by a programmer.

Regal & Skyhawk Models

On Regal and Skyhawk models, a programmer permits use of vacuum-operated actuators instead of electric actuators. The programmer is located directly below the temperature door actuator.

The programmer contains 4 vacuum solenoids. Signals generated by the A/C control head provide the programmer with the necessary drive impulse to ground a vacuum solenoid's individual coils. These solenoids then send vacuum to whichever actuator that will fill the systems needs at that time. By these means, the programmer has full control over what type and duct air will flow from.

On Electra and LeSabre sedans the programmer is attached to the A/C module assembly behind the glove box within the passenger compartment. The programmer consists of a small 8 volt DC motor and variable resistor (potentiometer) with an air-mix (temperature) valve position feedback center tap, 4 vacuum solenoids, and electronic switching amplifiers and drivers are mounted to a printed circuit board. The programmer accepts low current command signals, which are initiated by the operator selected mode key pad switch positions and the 2 temperature sensor readings.

The programmer energizes specified solenoids with a constant 12 volt DC level by grounding one side of the solenoid through the designated electronic switch (located in the control head PC board). Vacuum is then applied to the selected vacuum motor actuators which reposition any one, 2 or all 3 valves to control airflow in the A/C module.

Note. No attempt should be made to repair the programmer's electronic circuits or vacuum solenoids. If programmer malfunctions, replace it.

BLOWER MOTOR & A/C CLUTCH CONTROL

The A/C clutch and blower motor control is located in the blower motor air stream in the engine compartment. The blower control feeds current to the blower motor through a variable range. In this way the blower speed can be varied to many different speeds. A power transistor circuit engages the compressor clutch when required. (Scheme 4)

Note. System should never be operated with blower motor disconnected, as damage will occur to blower and A/C clutch control.

Scheme 4

BLOWER POWER CONTROL MODULE

The blower power control module is mounted on top of the evaporator and blower module in engine compartment. It regulates blower motor speed in response to a controller generated command signal. The module's main function is to convert these low voltage command signals into high voltage blower current.

If temperature door actuator arm is out of adjustment, temperature mode lights will flash at either "65°" or "85°" panel position. To adjust, touch "85°" panel temperature setting, pull door rod toward inside of car and snap rod into actuator retainer at that position.

TEMPERATURE DOOR LINK ROD

1. Disconnect actuator rod from actuator crank arm. Select "85°" position then, after the motor stops, pull the rod down as far as it will go.
2. Adjust the connector position so rod snaps in place in that position.

Rear Window Defogger Does Not Work (Electra & LeSabre Sedans)

1. Check for open rear defogger relay. Check wiring harness and connectors for opens between power source, rear defogger relay and rear window heater grid. Repair as necessary.
2. Check for malfunctioning electronic switch in A/C controller. This switch provides a timed ground return for rear defogger relay coil. Using an ohmmeter, check rear defogger heater grid for continuity. Repair as necessary.
3. Check circuit breaker No.24 for voltage output. This relay supplies the rear defogger heater grid with a 12 volt power source. Repair or replace as necessary.

Insufficient Heat or No Heat (Electra & LeSabre Sedans)

1. Check in-car and outside temperature sensors for correct calibration. See «SENSOR CALIBRATION»(/buick/electra/vi-1985-1990/remont/automatic-hvac-system/#ac-heater-system-automatic) in this article. Check for correct temperature valve position based on A/C controller generated signal voltage.
2. To check valve position, remove glove box. Disconnect link arm from actuator. Move temperature valve through its complete cycle to check for sticking or binding. If okay, reconnect link arm and adjust. See «TEMPERATURE DOOR LINK ROD»(/buick/electra/vi-1985-1990/remont/automatic-hvac-system/#ac-heater-system-automatic__temperature-door-link-rod) adjustment procedure in this article.
3. Turn ignition on, select "HEAT" mode, "85°" temperature and "HI" fan positions. Observe whether link arm moves to full heat position. If no movement is observed, either the programmer or the A/C controller is at fault.
4. Remove and replace the programmer with a known good unit. Then repeat step 3. If no movement of the linkage is observed, remove and replace the A/C controller.

A/C Compressor Doesn't Work or Clutch Won't Cycle (Electra & LeSabre Sedans)

1. Check the A/C select switch relay for opens. Warm engine to operating temperature and shut off. Using a ohmmeter check relay coil for an open between pins A and C of A/C select switch relay. If open, replace relay.
2. Using an ohmmeter, check the continuity of the wiring between and through the compressor clutch coil. If no continuity is found, repair wiring or replace compressor clutch coil.
3. If okay, turn ignition on and select the "AUTO" mode. Using a voltmeter, check for voltage drops between pins A and C of A/C select switch relay. If 12 volts are found at both relay terminals, remove and replace A/C control head panel.
4. Check the compressor clutch diode for short to ground. Turn ignition off. Disconnect Dark Green wire from compressor clutch. Using a multimeter, check compressor diode for short to ground. If shorted, replace.

No Blower or Erratic Blower Operation (Electra & LeSabre Sedans)

1. Check for open blower motor winding. Using an ohmmeter check the winding resistance value. It should be 1.1-1.3 ohms. If open or not within specifications, replace motor.
2. Using an ohmmeter, check for continuity between blower module ground terminal pin 5 and ground, and the ground terminal harness connection to the blower motor and ground lug. If no continuity is found, repair wiring and recheck continuity to the dash ground. If okay, go to step 3. If not okay, repair ground.
3. With ignition on and blower off, using a voltmeter, check for 12 volt feedback voltage outputted from blower module pin 3, and inputted at A/C controller pin L. If not okay, use voltmeter to check for 12 volt input to blower power control module. If okay, go to step 4. If not okay, check power feed to blower power control module.
4. With ignition off disconnect power feed wire, blower motor Red terminal. Connect a fused (25 amp) jumper wire between the positive motor terminal and a 10 volt power source. If motor does not run, runs slowly or the motor bearings are noisy, remove and replace the motor. If motor runs smoothly and quietly, remove jumper and reconnect feed harness connector to motor.

System Operates Only at Maximum A/C (Electra, LeSabre Wagons, Regal & Skyhawk Models)

1. Select "85°" setting. If system remains in maximum A/C, proceed to TEMPERATURE VALVE ACTUATOR. If system goes to heat, check for the following: A short in either the in-vehicle or outside ambient temperature sensor. Incorrect sensors. Shorted wiring at sensor connections. Control panel out of calibration. NOTE: Control panel should not be recalibrated unless sensors have been changed or panel has been recalibrated earlier.
2. If none of the above conditions exist, proceed to TEMPERATURE VALVE ACTUATOR.

System Operates Only at Maximum Heat (Electra, LeSabre Wagons, Regal & Skyhawk Models)

1. Select "65°" temperature setting. If system goes to maximum cool, check the following: An open sensor string. Disconnected in-car or ambient temperature sensor, broken or disconnected wires in sensor wiring system. An incorrect sensor installed or sensor malfunction.
2. If none of the above conditions exist, proceed to TEMPERATURE VALVE ACTUATOR.

System Does Not Provide Comfort at Control Panel Setting (Electra, LeSabre Wagons, Regal & Skyhawk Models)

Check for proper operation or adjustment of the following components

1. Aspirator System - Airflow should hold small piece of paper against in-vehicle temperature sensor grille. If not, check for disconnected hose.
2. Sensor Operation - Be sure in-vehicle sensor box cover is in place.
3. Temperature Actuator Door Link Rod - Check door rod for sticking or binding.
4. Temperature Actuator Door and Link Rod Calibration - Check calibration by watching door movement. It should move toward front of car in "65°" setting. Choose "85°" setting. Arm should rotate at least 180°. If out of adjustment, LEDs will flash at "65°" or "85°" position.

Mode Actuator - Regal & Skyhawk

Note. Engine must be running, battery must be fully charged, and system must be receiving at least 10 volts during this check.

1. If mode actuator will not move, check for vacuum at port 5 of programmer vacuum connector. Check for 12 volts at pin F of programmer. If either voltage or vacuum is missing, check vacuum and wiring harness.
2. If airflow to 2 or more actuators is incorrect, check vacuum connections at programmer. (Scheme 23)and (Scheme 24). Check for proper electrical connection at programmer.
3. If problem still exists, check lower mode actuator. Disconnect Red vacuum hose from heater side. Select "85°" and "AUTO" settings. If vacuum is present, go to step 4. If not, proceed to step 6.
4. Disconnect Yellow vacuum hose at A/C side. If vacuum is present, go to step 10. If no vacuum is present, replace hose and go to step 5.
5. Select "65°" setting. If no vacuum is present at Red hose on heater side, check programmer. If vacuum is present at Red hose, check lower mode door for obstructions. If none, replace mode actuator. If vacuum is now present, go to step 7.
6. Using a voltmeter, check voltage at programmer pin D (Regal) or pin E (Skyhawk). If voltage is more than 8 volts, go to step 8. If less than 8 volts, substitute with a good programmer.
7. Repeat voltage check in step 6. If voltage is now greater than 8 volts, install new programmer. If still less than 8 volts, proceed to step 9.
8. Check voltage at pin 4 (Regal) or at pin E (Skyhawk) of control panel 22-pin connector. To do so, insert probe through rear of connector. If voltage is more than 2 volts, replace control unit.
9. If less than 2 volts, check wiring and connections between pin D of programmer and pin 4 of 22-pin connector (Regal) or pin E of programmer and pin E of 22-pin connector (Skyhawk).
10. If, in step 7, voltage was less than 8 volts, insert probe through rear of connector. Check voltage at pin 4 (Regal) or at pin E (Skyhawk) of control panel's 22-pin connector. If voltage is less than 2 volts, replace control panel.
11. If more than 2 volts, check wiring and connections between pin D of programmer and pin 4 of 22-pin connector (Regal) or pin E of programmer and pin E of 22-pin connector (Skyhawk).
12. Check voltage at programmer pin B (Regal) or pin D (Skyhawk). If it is greater than 8 volts, replace the programmer. If less than 8 volts, check voltage at pin 3 (Regal) or pin 7 (Skyhawk) of 22-pin connector.
13. If voltage is less than 2 volts, replace control panel. If voltage is more than 2 volts, check electrical connections and wiring between programmer pin 3 and pin B of 22-pin connector (Regal) or between programmer pin 7 and pin D of 22-pin connector (Skyhawk).
14. If airflow from any other actuator is incorrect, disconnect vacuum hoses from actuators and follow the procedures outlined. If more than one actuator is suspected, work on each separately.
15. Select "65°" and "AUTO" settings. If no vacuum is present at hose to particular actuator, proceed to step 17. If vacuum is present, select "85°" and "AUTO" settings.
16. If vacuum is still lacking to a particular actuator, check mode door for obstructions. If no obstructions are found, replace actuator. If vacuum is now present, proceed to step 18.
17. Check voltage at appropriate pin on programmer. If voltage is less than 8 volts, replace programmer. If greater than 8 volts, proceed to step 19.
18. Check voltage at appropriate pin on programmer. If voltage is less than 8 volts, proceed to step 20. If voltage is more than 8 volts, replace programmer.

The following quick check procedure should be used to determine if A/C system is operating properly, or to verify customer complaints. Before conducting quick check procedures, warm engine to operating temperature. Turn ignition on, then off and back to on again. This is to determine if the LED lights are operating. The previously set A/C mode and guide temperature reading should be indicated at this time. Perform the following checks

1. Turn ignition switch to "ON" position. Allow a minimum of 3 minutes before initiating step 2. Allow the blower delay timer to cycle and allow the heater and bi-level modes to function.
2. Press "WARM" key pad until display indicates "85°". Depress "WARM" mode key pad again. Display should read "90°" (maximum heat).
3. Press "COOL" mode key pad until display indicates "65°". Depress "COOL" mode key pad again. Display should read "60°" (maximum cool).
4. Leave the selected display temperature at "60°" and depress "AUTO" mode key pad. Wait approximately 5 seconds. If the "AUTO" LED flashes, check for a problem with the outside air/ recirculation mode actuator.
5. Press "HEAT" mode key pad. Observe if "HEATER" mode LED is lit. Wait approximately 5 seconds. If the "HEAT" LED flashes, check for a problem with the A/C/defrost mode actuator.
6. Press "DEF" key pad. "DEF" LED should light. If it flashes, check for a problem with the A/C-defrost mode actuator.
7. Press "OFF" mode key pad. Compressor clutch should disengage and fan speed should reduce to 0 speed. If the "OFF" mode LED flashes, check for a problem with one of the mode actuators (noted in a previous step).
8. Press "ECON" mode key pad. Compressor clutch should be disengaged. The "ECON" LED should be lit. If it flashes, check for a problem with one of the mode actuators (noted in a previous step). Compressor clutch should be disengaged.
9. Press "LO" fan mode key pad. LED should light. Within 10 seconds, fan should be at or decrease to low speed. Press "HI" mode button, LED should light. Within 10 seconds, fan speed should increase to maximum.
10. Depress "EXT TEMP" mode key pad. The LED should light as the display indicates outside ambient temperature. If LED flashes, one of the following components is either shorted or open: In-car sensor, outside air sensor or air-mix feedback potentiometer.
11. Pressing the "EXT TEMP" mode key pad again should cause the display to read the temperature selected and the "EXT TEMP" LED should dim. Set selected temperature to "74°" and set fan speed to "LO". Press the "BI-LEV" mode key pad. Then, turn the ignition switch to "OFF" position and wait 5 minutes.
12. Turn ignition switch to "ON" position. Display should read "74°" prior to turning the ignition to "OFF" position. Turn park light switch to "ON" position. Rotate dimmer rheostat and observe whether front panel and digital LEDs dim.
13. If the vehicle has the rear defogger option, depress "RDEF" mode key pad and observe whether the LED brightens in intensity and the rear window defogger grid warms the glass.

Electra & LeSabre Sedan Models

Note. Diagnostic codes for climate control system were not available from manufacturer.

Depressing the hidden diagnostic switch will reveal diagnostic codes that identify the condition, open or shorted, of both the in-car and outside air temperature sensors. A "00" code indicates no identifiable sensor or air-mix valve problems at time of test.

Electra, LeSabre Wagons, Regal & Skyhawk Models

Note the following information when testing control system

1. "65°" selection drives system to maximum cold.
2. "85°" selection drives system to maximum heat.
3. A mode LED will flash if mode is malfunctioning (Electra, LeSabre sedans only).
4. A temperature LED will flash if temperature control actuator malfunctions (Electra & LeSabre wagons and Regal & Skyhawk models).
5. A disconnected mode door actuator wire will cause mode LEDs to flash.
6. An inoperative mode door, which is stopped in a position correct for one mode, will not cause LED to flash until control panel calls for actuator to move to another position.
7. Blower delay timer is engaged only when system senses it should be putting out heat in "ECON", "AUTO-LO", "AUTO" and "BI-LEV" modes. Check timers by selecting "HI" and "65°" on control panel. There should be no delay in system operation.
8. To further check blower delay timer, select a high guide temperature setting and one of the previously mentioned modes. Timer should engage, keeping blower off for 3 minutes, until coolant has had a chance to warm up. Blower should then engage. In "A/C", "DEF" and "HI" modes, blower delay timer will not function. It will not operate when engine is warm.
9. Control panel must have a constant power from ignition switch to work properly.
10. An open sensor circuit will drive the system to maximum heat except at "65°" selection.
11. A shorted sensor circuit will drive the system to maximum cold except at "85°" selection.

1. Turn ignition on and select "75°" and "AUTO" positions. These LEDs should glow, if not check fuse block for blown A/C fuse. Use a test light to check power feed wire (pin B of 22-pin connector) for shorts, opens or disconnection.
2. Switch the ignition off and on several times. Check to see that the "75°" temperature and the "AUTO" mode setting LEDs glow each time. If temperature or mode setting change each time the ignition switch is turned on, it is likely that the "B" feed wire is disconnected or is not supplying a consistent 12 volts. Repair or replace wiring as necessary.
3. Check pin "B" in the center (six-pin) connector in the back of control head panel for looseness, dirty mating tabs or broken wires. It is possible that neither of these LED bulbs are working, check by using alternate temperature and mode selection. If problem persists, replace control panel.

CONTROL PANEL SIGNAL/VOLTAGE (1 of 2). Scheme 5

CONTROL PANEL SIGNAL/VOLTAGE (2 of 2). Scheme 6

1. With engine running and at operating temperature, select "65°" and "AUTO" positions. The blower should gradually increase to maximum blower speed. If not, refer to «BLOWER CONTROL DIAGNOSIS»(/buick/electra/vi-1985-1990/remont/automatic-hvac-system/#ac-heater-system-automatic) . Air should be cold and flowing from A/C registers. The recirculation door should be open, and the temperature door should go to maximum cool. If either of these actuators is not functioning properly, the "AUTO" LED will flash.
2. Select "85°" and "AUTO" positions. Blower speed should decrease, then gradually increase to maximum. If not, refer to «BLOWER CONTROL DIAGNOSIS»(/buick/electra/vi-1985-1990/remont/automatic-hvac-system/#ac-heater-system-automatic) . If the temperature actuator does not go to maximum heat position, the "AUTO" LED will flash. If the mode doors are not in proper position the lower section LEDs will flash.
3. Select "85°" and "DEF" positions. Blower speed should remain at maximum speed. If not, refer to «BLOWER CONTROL DIAGNOSIS»(/buick/electra/vi-1985-1990/remont/automatic-hvac-system/#ac-heater-system-automatic) . In this mode output air should be hot. If not, the temperature LEDs should flash indicating a problem with temperature door. If the outside air temperature is above 50°F (10°C), the compressor will cycle. If not, refer to «CLUTCH CONTROL DIAGNOSIS»(/buick/electra/vi-1985-1990/remont/automatic-hvac-system/#ac-heater-system-automatic__clutch-control-diagnosis) . If the defroster door does not go to its correct position, the lower section LEDs will flash.
4. Select "75°" and "BI-LEV" positions. All air should be flowing from A/C and heater registers. If there is a problem, the "BI-LEV" LED will flash. Blower speed should slow, if not there may be a sensor problem. If the temperature door does not reach its new position, the "75°" LED will flash.

1. With engine running and at operating temperature, select "65°" setting, wait 60 seconds, then select "85°" setting. This drives the temperature door to its extreme position, first maximum cold, then maximum hot.
2. If LEDs do not flash when door position was changed, the component is operating properly. If LEDs do flash in either position, the temperature door is out of adjustment.
3. If the actuator arm is out of adjustment, it will bottom out while moving the door. If the door is out of adjustment, the temperature LEDs will flash at the "65°" or "85°" position. To adjust, see «TEMPERATURE DOOR LINK ROD»(/buick/electra/vi-1985-1990/remont/automatic-hvac-system/#ac-heater-system-automatic__temperature-door-link-rod) adjustment in this article.

Make sure vacuum lines to the vacuum connector block are tight and vacuum lines are connected to the correct ports. Check for 12 volts at pin F of 6-way programmer electrical connector.

PROGRAMMER INDEXING

PROGRAMMER ELECTRICAL INDEXING

1. Check voltage at appropriate pin in 22-pin control panel connector. If voltage is less than 2 volts, check electrical connections and wiring between control panel and programmer. If voltage is more than 2 volts, replace control panel.
2. Check voltage at appropriate pin in 22-pin control panel connector. If voltage is more than 2 volts, check electrical connections between control panel and programmer. If less than 2 volts, replace control panel.

Scheme 7

1. Use airflow to determine which mode actuator is malfunctioning. Check electrical connection to faulty actuator. Check actuator after touching LED (restores power for 20-second period). If motor runs more than 15-20 seconds, proceed to step 16. NOTE: Electrical problems with either mode or temperature actuator circuits will flash LED on panel whether problem is with actuator, control panel or wiring. Conduct functional tests prior to diagnosis.
2. If actuator is inoperative, go to step 3. If it stops at incorrect position, go to step 12. If it stops at correct position but door fails to seal, go to step 15. Test with known good actuator. NOTE: Actuators are interchangeable ONLY for testing, not for normal operation. Also, 2-position actuators cannot be used to check 3-position actuators.
3. If actuator was inoperative when flashing LED was pushed, turn ignition on. Attach positive voltmeter lead to actuator pin C and ground. If voltage is 8 volts or more, go to step 7. If less than 2 volts, go to step 9. If voltage was between 2 and 8 volts, go to step 4.
4. Check for bad connections between battery and fuse block, fuse block and pin B of control panel 22-pin connector, or pin C of 22-pin connector and actuator.
5. Also check for malfunctioning diode in control panel. To do so, check voltage-in reading at pin B and voltage-out reading at pin C of 22-pin connector. If more than one volt difference, diode is malfunctioning. Replace control panel.
6. If voltage difference is one volt or less, but voltage at pin B is less than 8 volts, check battery charge and connections. If voltage difference is correct, but pin C voltage was less than 8 volts, replace control panel.
7. If more than 8 volts were indicated in step 3, attach voltmeter to actuator pins A and C. Touch flashing mode LED on panel, and observe voltmeter reading.
8. If voltage was 8 volts or more, check for obstruction of links or mode doors. Also check for stripped actuator gears. If no problems are found, replace actuator. Be sure control panel shuts off power after 20 seconds when a malfunction occurs. If voltage indicated in step 7 was less than 2 volts, go to step 11.
9. If voltage in step 3 was less than 2 volts, connect voltmeter positive lead to pin C of 22-pin connector (ignition voltage source for all actuators). Connect negative lead to ground. Check voltage.
10. If reading is more than 8 volts, wire from pin C is either shorted, broken, or has a poor connection. If less than 2 volts is indicated, replace control panel.
11. If voltage in step 7 was less than 2 volts, connect voltmeter leads to pin C of 22-pin connector and actuator wire connector terminal A. Touch flashing LED and check voltage. If voltage is 8 volts or more, check continuity of wires. If less than 2 volts, replace control panel.
12. If in step 2 the actuator stopped at incorrect position, turn ignition on and check for flashing mode LED. Attach a voltmeter to actuator pins A and D. Touch flashing mode LED and check voltage.
13. Voltage should cycle between 11 volts and 5 volts. If so, check continuity of wire connecting actuator pin C to control panel 22-pin connector. If continuity exists, replace actuator.
14. If in step 13 no voltage change occurred, replace actuator. If voltage changes occurred, but were not within specifications, replace control panel.
15. If in step 2 the actuator stopped at the correct position, but door was in incorrect position, check door link attachments and assembly to actuator. Check actuator adjustment, making sure actuator arm is in correct position based on control panel setting.
16. If in step 1 the motor ran more than 15-20 seconds, turn ignition off and remove connector from actuator. Using a self-powered test light, check continuity from actuator pin A to ground.
17. If test light lights, there is a short in harness. If it does not light, check continuity of wire from actuator pin D (signal connection) to control panel 22-pin connector. If wire is okay (test light lights), replace actuator. If wire is open or grounded (light does not light), repair harness.

Scheme 8

1. If temperature actuator sub-system is suspected, inspect actuator arm for obstructions. Check door rod for binding and proper adjustment. Check electrical connections to actuator.
2. If no problems are found, apply 12 volts across terminals A and B of actuator for 2-3 seconds. Note actuator arm movement. Reverse leads to terminals A and B for 2-3 seconds. Again note actuator arm movement.
3. If arm moves both ways, drive circuit is okay. Proceed to next step. If actuator runs, but arm fails to move, gears within actuator are stripped. Replace actuator.
4. Using an ohmmeter, check resistance between actuator terminals C and D. At 68-86°F, resistance should be 1100 ohms. If correct, proceed to next step. If ohmmeter reads infinity, suspect a broken resistor strip. Replace resistor strip.
5. Apply 12 volts to actuator terminals A and B. Drive arm to calibration point and take resistance reading between actuator terminals C and F. Reading should be 670 ohms. If not, a feedback circuit failure requires actuator replacement.
6. Check continuity of electrical wiring and connections between actuator and control panel. If continuity is okay, replace control panel.

No Blower At "65°" Temperature Setting (Electra, LeSabre Wagons, Regal & Skyhawk Models)

1. With engine warm and not running, ignition on, connect a voltmeter between blower control terminals 1 and 7 leaving connector attached. (Scheme 9) If voltage is fluctuating above 3 volts, go to step 2. If voltage is less than 3 volts, go to step 3.
2. Connect a voltmeter between the blower feed pin 6 and ground pin 7, with connector connected. If 3 volts or more are evident, the blower motor is malfunctioning or is improperly grounded. Repair or replace as necessary. If less than 3 volts are evident, the blower control must be replaced.
3. Connect a voltmeter between pin B of the 8-way connector at the control head panel, and a suitable ground. If less than 3 volts are evident, the control head panel must be replaced. If voltage is fluctuating above 3 volts, check the circuit continuity and repair as necessary.

Scheme 9

No Blower at "85°" Temperature Setting

1. With the ignition on, the engine off and at normal operating temperature, run the system for at least 3 minutes before beginning diagnosis. Select "65°" temperature setting. If blower runs, go to step 2. If no blower, refer to NO BLOWER AT "65°" TEMPERATURE SETTING.
2. Check the terminal connections at the blower and A/C clutch control. If blower comes on, clean and reconnect terminals. If no blower, blower delay timer is malfunctioning. Replace the control head panel.

High Blower Only, No Blower at "LO" Position

With the engine off, the ignition on, the engine at normal operating temperature, connect a voltmeter between blower control pins 1 and 7. If voltage is greater than 3, but less than 7 volts and fluctuates, replace the blower control. If voltage fluctuates above 7 volts, replace the control head panel.

No High Blower in "HI" or "DEF"

1. With ignition on, the engine off and at normal operating temperature, connect a voltmeter between blower control pin 1 and ground pin 7. If greater than 3, but less than 7 volts are evident and fluctuating, replace the control head panel. If greater than 7 volts are evident and fluctuating, go to step 2.
2. Connect a voltmeter between blower feed pin 6 and ground pin 7. If 11 to 14 volts are evident, replace the blower motor. If voltage is less than 10 volts replace the blower control.

Blower Speed Does Not Vary in "ECON", "AUTO", "HEAT" or "BI-LEV"

1. With ignition on, the engine off and at operating temperature, connect a voltmeter between blower control pin 1 and a suitable ground. Select the "65°", then the "85°" temperature setting and the "AUTO" mode. Observe the voltmeter.
2. Voltage should just fluctuate above 7 volts, then below 7 volts and then back above 7 volts. If this occurs, go to step 3. No fluctuation in voltage indicates a defective control head panel which must be replaced.
3. Connect a voltmeter between blower feed pin 6 and a suitable ground. Touch the "65°" temperature setting, then the "85°" temperature setting in the "AUTO" mode. If the voltage changes from 12 volts to 3 volts and then back to 12 volts, an inoperative blower motor is indicated. Replace as necessary. If no change in voltage is evident, replace the blower control.

CLUTCH CONTROL DIAGNOSIS

Note. If clutch does not engage above 50-55°F (10-13°C), first check compressor clutch diode, and then begin diagnosis. Engine should be running. A control panel temperature and mode LED should be lit in "A/C", "BI-LEVEL", or "DEFROST" modes.

Electra & LeSabre Wagons & Regal Models

1. Connect voltmeter between compressor clutch output pin 5 and ground. If 8-12 volts are present, suspect malfunctioning clutch or pressure switch or a poor ground.
2. If zero volts are present, connect voltmeter between clutch control input pin 3 and ground. If 8-12 volts are present, proceed to step 3. If less than 8 volts check the continuity of the ignition wire between the blower clutch control and the control panel. Repair or replace as necessary.
3. Connect voltmeter between compressor clutch input pin 4 and ground. If 4-6 volts are present, go to step 4. If 10 volts or more are present, go to step 5. If 3 volts or less are present, go to step 6.
4. Use a jumper wire and connect pin 5 directly to compressor clutch. If clutch engages, either R-12 charge is low, pressure switch is inoperative, or one of the control devices is stopping operation. Replace the control device or recharge the system, as necessary. If clutch does not engage, the blower/clutch control assembly is inoperative and must be replaced.
5. Connect a voltmeter at control panel pin C of 8-pin connector and to ground. If 10 volts or greater are read, replace the control panel. If less than 10 volts are read, the wire from pin C on the control head to clutch control input pin 4 is open.
6. Check the continuity of wire from pin C on control head to clutch control input pin 4. Be sure the wire is not shorted to ground. If the wire is shorted to ground or broken, replace the wire. If wire is okay, replace the control head.

1. Connect a voltmeter between compressor clutch output pin 4 and ground. If 8-12 volts are present, suspect malfunctioning clutch or pressure switch or a poor ground.
2. If zero volts is read, connect a voltmeter between clutch control input pin 5 and ground. If 8-12 volts are present, proceed to next step. If zero volts are indicated, proceed to step 5.
3. Connect a voltmeter between ignition feed and pin 3 and ground. If 8-12 volts are present, proceed to next step. If less than 8 volts, check continuity of ignition wire between control and control panel. Repair or replace as needed.
4. Use a jumper wire and connect pin 5 directly to compressor clutch. If clutch engages, either R-12 charge is low, pressure switch is inoperative, or one of the control devices is stopping operation. Replace the control device or recharge the system, as necessary. If clutch then does not engage, the blower-clutch control assembly is inoperative and must be replaced.
5. Connect a voltmeter to pin B of 22-pin connector at control panel and ground. If 8-12 volts are present, a poor connection or broken wire is at fault. Check wiring and repair as necessary. If less than 8 volts are present, replace control panel.

Scheme 10

1. If an ambient or in-car temperature sensor is suspected, disconnect sensor, and take a resistance reading across sensor terminals. If resistance reading is not within 5% of ideal curves indicated in graph, replace sensor. (Scheme 10) NOTE: Resistance readings may vary by 5% from ideal.
2. If resistance is within specification, check continuity of wires from control panel to sensors. If wires are OK, control panel is defective.

System Response - Electra & LeSabre Wagons. Scheme 11

System Response - Regal. Scheme 12

SYSTEM RESPONSE - SKYHAWK

SYSTEM RESPONSE - ELECTRA & LESABRE SEDANS

TOUCH CONTROL SETTING

Electronic Touch Climate Control (Electra). Scheme 13

Electronic Touch Climate Control (Le Sabre). Scheme 14

Electronic Touch Climate Control (Regal). Scheme 15

Electronic Touch Climate Control (Skyhawk). Scheme 16

REMOVAL & INSTALLATION

Note. Disconnect battery before replacing any component.

All Models

1. Discharge A/C system using approved refrigerant recovery/recycling equipment. Remove low pressure return lines at both the inlet and outlet accumulator connections. Remove pressure cycling switch connection.
2. Remove switch. Loosen the lower bracket bolt and spread the bracket. Rotate the accumulator and remove.
3. To install, reverse removal procedure. Transfer switch to new accumulator. Evacuate and charge A/C system.

EVAPORATOR WITH HEATER CORE

Note. The following procedures are for vehicles with air conditioning only. For vehicles with heater systems only, see GENERAL MOTORS PASSENGER CARS article in HEATER SYSTEMS section.

1. Disconnect negative battery cable. Discharge A/C system using approved refrigerant recovery/recycling equipment. Drain engine cooling system. Remove engine compartment right-hand relay shield. Remove relay bracket from fender. Disconnect A/C lines from accumulator.
2. Disconnect connector from cycling switch. Remove accumulator and bracket. Remove A/C line evaporator. Remove power steering pump mounting bolts. Set power steering pump aside.
3. Disconnect spark plug wires from Nos. 2, 4 and 6. Disconnect wiring to coil assembly. Remove coil bracket and lay coil assembly aside. Remove vacuum tank. Remove blower motor. Remove exhaust manifold shield. Disconnect heater hoses from heater core.
4. Remove blower resistor. Remove lower right-hand instrument trim panel. Remove heater floor ducts. Remove bolts attaching evaporator case. Remover evaporator. To install, reverse removal procedure.

Blower Module Assembly. Scheme 17

Module Wiring Harness. Scheme 18

A/C Heater & Evaporator. Scheme 19

1. Disconnect negative battery cable. Drain engine cooling system. Remove splash cover to access heater hoses.
2. Disconnect heater hoses from heater core. Remove right sound insulator and center instrument panel trim plate. Remove lower instrument panel trim plate. Disconnect wires and hoses from programmer. NOTE: Step 3 is for Tempmatic (C65) only.
3. Remove programmer linkage cover and linkage. Remove programmer attaching bolts and programmer. Remove heater core cover.
4. Remove heater core. To install, reverse removal procedure.

Remove glove box. Remove steering column trim cover, right and left hush panels and heater outlet duct. Remove nuts attaching actuator to bracket and remove actuator. To install, reverse removal procedure.

1. Remove instrument panel trim plates and screws from control. Remove steering column trim cover (if necessary). Pull control out from instrument panel and disconnect electrical connectors.
2. If replacing bulb, remove 4 screws from front and 2 screws from bottom of panel. Carefully push on electrical prongs at rear of control assembly. Slide assembly out of case.
3. Remove top or bottom bulb by pulling out on circuit board. To install, carefully slide circuit board into case within guide tracks. (Scheme 20) Replace control, screws, and trim panel.

Scheme 20

Electra & LeSabre Sedans Only

1. Carefully lift and remove trim plate from control head panel. Remove 4 screws holding control head to instrument panel. Disconnect electrical connector from rear of control head.
2. Remove 2 clips holding faceplate to plastic housing. Carefully push out male electrical connector at the back of the controller while simultaneously releasing 2 plastic clips on housing. Slide main printed circuit board out from front of case.
3. Carefully remove and replace bulbs in case (if needed). Slide printed circuit board into case and replace 2 clips securing key pad panel to case.
4. Reconnect electrical connector. Reinstall 4 case mounting screws and control head trim plate.

CONDENSER R & I

1. Discharge A/C system using approved refrigerant recovery/recycling equipment. Disconnect high pressure line to condenser. Disconnect liquid line to condenser.
2. Remove grille center support and 4 screws securing condenser. Remove condenser. To install, reverse removal procedure. Evacuate and charge A/C system.

Installation - All Models Except Skyhawk

1. Disconnect negative battery cable. Discharge A/C system using approved refrigerant recovery/recycling equipment. Hoist vehicle and remove electrical connectors from front and rear of compressor.
2. Remove bolt attaching refrigerant lines at rear of compressor. Loosen front upper mounting bolt. Loosen front lower belt tension adjusting bolt. Loosen rear bracket bolt and spacer.
3. Remove belt. Remove 3 bolts securing compressor. Remove air injection pipe and check valve. Remove compressor by sliding towards starter and down.

Removal

1. Position compressor on bracket. Install top mounting bolt loosely. Install belt tension adjusting bolt loosely. Install rear bracket bolt and spacer loosely.
2. Install bolt and refrigerant lines to rear of compressor. Install belt and remove slack by using a 1/2" drive ratchet in hole of mounting bracket.
3. Tighten the belt tension adjusting bolt, top mounting bolt and rear bracket bolt and spacer. Connect negative battery cable. Evacuate and charge A/C system.

Removal & Installation - Skyhawk

1. Disconnect negative battery cable. Discharge A/C system using approved refrigerant recovery/recycling equipment. Hoist vehicle and remove right air dam and splash shield from rear of compressor.
2. Disconnect electrical connections at the compressor switch. Remove refrigerant lines at rear of compressor. Remove compressor attaching bolts, and compressor. To install, reverse removal procedure. Evacuate and charge A/C system.

Remove glove box, right and left hush panels and heater outlet duct. Remove vacuum actuator bracket from module. Remove actuator from bracket. To install, reverse removal procedure.

HEATER CONTROL VALVE & ACTUATOR R & I

1. Actuator or heater control valve may be removed separately. To remove actuator, select "85°" position prior to disconnecting battery. This will position valve and actuator in open position.
2. Remove electrical connector and screws. Remove actuator. To install, reverse removal procedure.

IN-CAR SENSOR R & I

1. Remove screws from instrument panel pad. Remove pad. Disconnect wire connector and hose from sensor and remove from panel. (Scheme 21)
2. On some models, it may be necessary to release locking latches on sensor as sensor is pulled out of instrument panel carrier. To install, reverse removal procedure.

Scheme 21

Remove glove box and right hush panel. Remove ECM mounting bracket screws and lower ECM for access. Remove actuator mounting screws and remove actuator. To install, reverse removal procedure.

Scheme 22

Scheme 23

Scheme 24

See also:
• SENSOR CALIBRATION
• TEMPERATURE DOOR LINK ROD
• CLUTCH CONTROL DIAGNOSIS