No air flow from vents in dash

DUANE L. WOLGAMUTH

MEMBER
1998 BUICK PARK AVENUE

Air conditioning problem six cylinder front wheel drive automatic 113,000 miles.

My air conditioning is blowing cold air but it directs the flow to the windshield and floor and not from the vents in the dash. It works this way in both the manual and automatic modes. I have checked the fuses under the dash (passenger side, far right, next to kick panel) and they are okay. It started doing this about three weeks ago and I could get it to work by pressing the auto button and then the off button, wait a couple seconds and press the auto button and the system would start blowing air out at the floor and then shift to the dash vents and work fine.

Every time you would shut the car off you would have to go through this sequence to get it to blow air out the vents. Now this no longer works. I am fairly handy and do not mind getting dirty, what should I look for and where. (Looks like a jungle under the dash and hood)! Note: Air flow indicator on dash indicates that the air should be coming out of the dash vents but it is coming out at the windshield and floor.

I checked the A/C and heater control per your suggestion. All functions of the control work as per the system response check, but the major air flow is at the windshield (defroster) regardless of the mode (auto, manual, floor, mid, recirculating, front, heat or cooling) that the controls indicate. There is a trace of air coming out of the heat ducts also but not the normal air flow, one could say that it is minimal.

I believe the control which switches the system to the different areas, windshield/floor/mid vents is not working, if so where is it, what has to be removed to get to it? Is there relay and if so where is it. I am assuming the control is electrical and not vacuum.

Had the computer scanned and no codes were present.

Thanks for your help.

8 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,643 POSTS

Hey Duane,

These cars also had problem with the blend door actuators (mode). What happens is the gears break inside the unit which will not trigger a code.

Here is a guide that will help you fix it:

https://www.2carpros.com/articles/replace-blend-door-motor

And diagrams (below)

Here is a testing procedure to help as well.

Try the following test.

DTC B1344: MODE DOOR MOVEMENT FAULT
1. Turn ignition switch to ON position. Connect scan tool. Activate suspect actuator. If door is being commanded to its correct high value of 100 percent, go to next step. If door is not being commanded to its correct high value of 100 percent, go to step 3).

2. Activate suspect actuator to lowest value. If door is being commanded to its correct low value of zero percent, go to step 4). If door is not being commanded to its correct low value of zero percent, go to next step.

3. Check programmer for good terminal contact. If terminal contact is okay, replace programmer.

4. Compare high and low actual values. If high values are 100-95 percent, and low values are 0-5 percent, go to step 11). If high and low values are not within specification, go to next step.

5. Check linkage between door and actuator. Check door for obstructions. If linkage and/or door are okay, go to step 9). If linkage and/or door are not okay, go to next step.

6. Disconnect actuator connector. Check voltage at actuator connector terminal No. 10 (Gray wire). If 5 volts are present, go to next step. If 5 volts are not present, go to step 10).

7. Disconnect actuator connector. Check voltage at actuator connector terminal No. 5 (Brown wire). If 12 volts are present, go to next step. If 12 volts are not present, go to step 10).

8. Disconnect actuator connector. Check Yellow, Yellow/Black, and Yellow wires for an open circuit. If an open circuit is present, go to step 10). If an open circuit is not present, go to step 11).

9. Repair door or linkage as necessary.

10. Repair open circuit in wiring.

11. Replace programmer.

Please run some tests and get back to us so we can continue helping you.

Best, Ken

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