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jazzmaster, ASE Certified Tech
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1997 Buick Park Avenue: vacuum..The 97..electronic

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1997 Buick Park Avenue A/C problem - going crazy.

Read all about vacuum issues, but they seem to only apply to 96 and prior. The 97 is the newer platform, and appears all electronic.

A/C is blowing out defrost and floor - not dash vents. This was after a Mobil 1 oil change place disconnected the temperature probe in the engine near the filter causing a warning light. Also caused a major oil leak. Bad experience.

Took it to a dealer. He said that the problem was an I/O error in the Heater and
The GM assessment by the dealer said the first issue was "104246 Internal Failure in A/C Programmer," which I purchased and installed. The car is getting a lot cooler now and has greater control over the A/C and heat, so that was certainly useful. The dealer said verbally that there was an I/O error in the old board.

The dealer had reported that the next problem was the Blend Door (they said this verbally) and wrote up the A/C Mode Actuator may require replacement - part 89018383. I removed the old one (the motor could no longer move the gears) and replaced it with another that was working fine. I can see it moving in its position.

With both these steps completed, though, I still have no air coming out the dash vents. I read another post claiming that the failure mode is to push air out the floor and defrost when the controller fails, but nothing to tell me if the "controller" is the same thing as the programmer, or the digital control module with all the buttons on the dash. I also haven't found a second post to confirm that statement.

Evidently the AC is the same on the 97-05 model year Park Avenues. It is NOT a vacuum issue (The hoses called out in all those tips on the internet don't even exist on the 97).

Any suggestions? I really don't want to pay the dealer another $125 to tell me new diagnostic codes if I don't absolutely have to do so.

hi, the controller is the dash panel head unit, the programmer is what controls or sends signals to the actuators,be it heat/a/c/door modes,defrost/vents/floor etc.,if you replaced the controller then the system has to be recalibrated this is done by turning the key on to the run position(do not start) and let it sit for 3 minutes ,this will give it a chance to recalibrate the actuators and modes to the right positions ,I would suspect the head unit (dash unit) may be bad

I am including the electrical diagrams for this system,











The heater and A/C control allows the vehicle operator to communicate with the electronic A/C system. The heater and A/C control includes soft-touch buttons to select operating modes, a fan speed increase/decrease switch, the rear defog control switch, and a vacuum fluorescent display panel. When the parklamps or headlamps are turned on, the buttons and switches are illuminated.

When any button on the heater and A/C control assembly is pressed the complete status of the HVAC system will be displayed. The display will indicate the status of the blower speed, mode and set temperature.

Mode Selector Button

The heater A/C control has a mode selector button for the following modes:

  • OFF
  • AUTO.
  • MID.
  • VENT.
  • FLOOR.
  • DEFOG.

Pressing any button except "AUTO" tells the HVAC programmer to set air intake point, set air discharge points, and activate or de-activate the A/C compressor, according to the mode selected.

Pressing "AUTO" tells the HVAC programmer to select the appropriate air intake and discharge points and activate or de-activate the A/C compressor, according to the operator selected "SET" temperature and information provided by the system's network of sensors.

Temperature Increase/Decrease Button

With the system in any mode but OFF and "SET" temperature between 18°C (65°F) and 29°C (85°F), pressing the increase or decrease end of the switch once increases or decreases "SET" temperature one degree. If the decrease end of the switch is pressed with "SET" temperature at 18°C (65°F), SET" temperature drops immediately to 15°C (60°F). If the increase end of the switch is pressed with "SET" temperature at 29°C (85°F), "SET" temperature jumps immediately to 32°C (90°F).

An increase or decrease of the "SET" temperature signals the HVAC programmer to take the steps necessary (change blower speed, change air discharge location, change air temperature) to bring the passenger compartment temperature to the new "SET" temperature.
With the system in the OFF mode, pressing either end of the temperature switch causes the system to turn on m the AUTO mode. The system displays the outside temperature approximately 10 seconds after the last change on the temperature knob, as well as when the system is in the OFF mode.

Fan Speed Increase/Decrease Button

The fan speed increase/decrease switch is used to manually change fan speed. Pressing the increase end of the fan speed switch once, increases the fan speed one level. Holding the increase end of the switch increases the fan speed until the switch is released or maximum fan speed is reached. Pressing the decrease end of the switch decreases fan speed in the same manner.

If the system is operating under AUTO fan speed control, moving the fan speed switch causes AUTO fan speed control to stop and manual fan speed control to begin. Fan speed remains constant, unless the increase/decrease switch is pressed again.

With the system in OFF mode, pressing either end of the fan speed switch causes the system to turn on in the AUTO mode with AUTO fan speed control.

Vacuum Fluorescent (VF) Information Display Panel

The VF panel provides system operating information for the driver.

The display panel has a three digit temperature display and the letters "°C" and "°F" appear on the display. The "°C" is illuminated when metric units are requested. The "°F" is illuminated for temperature display in English units. The words "EXT TEMP" and "AUTO" appear to the left of the temperature display. "EXT TEMP" is illuminated whenever outside temperature is displayed. "AUTO" turns on when "AUTO" mode is selected.

The blower speed is displayed in the form of the number of bars illuminated. One bar illuminated indicates low blower speed. Six bar illuminated indicates high blower speed. When the system is operating in AUTO mode, with AUTO fan speed control, no indicators art illuminated. Instead, the words AUTO illuminates. When the system is turned OFF, the fan speed display area is blank and the outside air temperature is displayed.

There are four actuators used to control the HVAC system. They are driver and passenger mix door actuators, a mode actuator, and an air inlet actuator. The actuators are specifically designed for the right and left side of the heater and A/C module. When servicing an actuator, be sure to replace it with the correct service part for the position being serviced.

A reversible DC motor in the actuator operates the door within the HVAC module.

The actuators contain a feedback potentiometer that informs the HVAC programmer of door position.


Customer: replied 5 years ago.
Thank you for the great info. Please let me check this solution set and get back to you.
jazzmaster and 4 other Buick Specialists are ready to help you
Customer: replied 5 years ago.
Sorry for the delay. I am accepting the answer. Wanted to check the solution.

Thank you for sharing the reset of the system. That was helpful. As it turns out the problem was/is that the mode door has broken inside the unit.

Your answer was still terrific, and I thank you for it. Accepting now. THank you again.