99 buick park avenue no air out of vents auto or not

I have 99 buick park avenue that will only blow out of the defroster. I expect one of the actuators to be bad but cant figure out which one. If someone can help I would appreciate it.

Look for vacuum leak under hood at vacuum reservoir- trace vacuum lines back to intake manifold- look for broken, cracked, mushy lines- replace or cut as necessary- this is most common issue.

The fact that all air goes to defrost is indicative that the vacuum supply is bad- the system is spring loaded to always clear the windshield if vacuum supply fails- Default to defrost is what it is referred to.

Purple hose is vacuum source behind glove box- but check for vacuum at reservoir under hood first.

update

took the lower actuator on the drivers side off as it just seemed to rock back and forth. when I took it off it still did the same thing. Is this the one that controls the air to the vents? Any help would be appreciated as I need to fix this before I install my new air conditioner compressor.

There is no vacuum associated with a 99 PA. I had a 96 PA that did have vacuum for the air diverters and it did the same thing. I replaced the hoses to the programmer and fixed that problem on the 96 but this is different.

If you have the dual zone system there should be two actuators on the driver's side. One is the mode actuator (defrost, vent, AC, etc.) and the other is the blend actuator.

Do you know which is the mode door?

According to the 1999 manual, the driver side air mix (temperature) actuator has to be removed to gain access to the mode actuator. If that makes any sense, the mode actuator is the "second" one in the arrangement.

one more question if anyone can answer if multiple actuators are not working could it be something else wrong?

I had the same problem with my 96 park avenue.behind the glove box,there is a vacuum terminal located on the ac/heater air box.there are several vacuum lines connected here.i dont know a lot of the technical names, but you will easily see this terminal.the lines are various colors.simply pressing this terminal fixed the air flow problem,but i would often have to repeat this step when again the air failed to blow out the vents.l later unpluged the terminal junction and sprayed a little wd40 or similiar lubricant into the vacuum lines and the ports they attached to.lasted 3or4 months before i had to repeat.very easily accessed these lines by lowering the glove box with a little force.whole process takes about 3 minutes.start to finish.hope this helps other uick owners.i know that the Japanese cars get a lot of credit for their reliability but this is my 5th used buick and they have never let me down.in my opinion,buick is the best car any american manufacturer has ever made.
My late uncle buren would say you could drive a buick til the wheels fell off and then pull the engine and use it to run a sawmill for another 20 years.thanks

For posterity, this a problem I am working now in my 98PA. Cold air flow restricted from the defrost vents and floor vents, with the fan blowing like crazy. No air from the dash vents no matter the air flow setting. Since there is a rubber tube that directs cooling air directly to the fan motor, it is not a good idea to try and use the HVAC with this condition.

I was doing that and suddenly smelled strong electrical smoke. The fan still works, but I may have damaged it.

I think there are four actuators, two on each side (left and right) of the HVAC housing. The "mode" actuator controls the air flow to the different vents. It is the one farthest from the firewall on the drivers side of the unit. Unfortunately it is a real bear to get out. The manual says to take the steering column out, and then the dash, even the aluminum support under all the plastic parts. The aluminum support is more or less moulded around the components to save space for the passenger compartment. I have cut an access hole in the support to see the actuator, because I didn't want to remove the column and dash.

The actuator is mounted very close to the support and you can easily cut the actuator unless you carefully use something like a Dremel to make shallow cuts. I realize that I am reducing the structural integrity and I may still need to remove the support.

The mode actuator has some complicated linkage that moves both the dash vent flaps and the door to direct air to the defrost in conjunction with each other. I may need to invest at Harbor Fright in one of those fiber optic scopes. This is the type of job that mechanics won't touch so you either do without cool and heat or do it yourself.

The other actuator on the drivers side is air temp mix. The two on the passengers side are air temp mix for the dual temp control, and the air inlet / recirculate actuator.

I did get the actuator out and it had the classic "split plastic gear" problem that keeps the actuator from moving the air doors. I replaced the gear with one from Ebay but re- installing the actuator and linkage may force the support removal. Story not complete yet.

The earlier PAs are not the same, the 1997 through 2005 are mostly alike.

The 97Park Avenue Blend actuator is just left of the glove compartment isn't it ?

No slig5440, if you read my post...the actuators on the drivers side of the HVAC unit are the mode actuator and an air temp mix actuator. The two on the passengers side of the HVAC unit are an air temp mix and the outsider inlet/interior air actuator.

I ended up taking the plastic off of the front of the dash and also the top of the dash, then cut a window in the aluminum support that goes across from the drivers side to the passenger side of the dash. I think you wouldn't need to take the top off if you were careful cutting the hole, but it is close.

I used a Dremel tool with a fiber cutting disc and felt up behind the dash to locate the actuator and the support rib on the back of the metal dash support. The mode actuator is within 3/8" of the back side of the support, so you need to be very careful of depth drilling any holes or with a saw. The Dremel or another rotary type tool will let you just barely cut through the 1/8" thick support.

If you would rather try to remove the mode actuator without the window/hole, then you will need to remove the air mix actuator first, then try for the mode actuator. It is very difficult to reach the screws that hold the actuators in place. I believe the screw head requires a 5.5mm or SAE equivalent. I'm really not sure you can do this. The factory manual says you must remove the complete metal support for the dash. That would mean a lot more work.

You need to look on the net or call a dealer to see what the mode actuator will cost. This will give you incentive to fix what you have. Also ask the dealer what they charge to do the job. The actuators are not cheap, but I suspect the labor is worse.

If you look closely at the pix, you will see the plastic linkage cover attached to the mode actuator. The actuator shaft goes thru the cover and is firmly connected to part of , under the cover. You must work thru the hole to remove the screws, then drop the mode actuator with cover down to the floor. Don't forget to remove the screw that is visible in the last pix, going thru the cover. You will need to remove the air mix actuator that is just a little closer to the firewall first to have room to work.

The black marker marks on the pix show where there is a rib on the back of the dash support. I did not wish to cut thru that rib, so the hole is just barely wide enough to work thru.

Under the cover are 3 white nylon air door linkage pieces (not visible). Take a pix of the linkage positions. Each one fits in grooves in the black cover piece and they slide in the grooves to move the air doors. You will need to get these back in their proper place for air door movement after fixing the actuator. Be very careful prying the mode actuator loose from the linkage. Take your time, it is very tight and if you break something, you will be buying a new one if you can find one. $$$ If you but a new actuator instead, it will come with the grove plate attached to the actuator. The other 3 actuators don't have this linkage cover attached. Check for pix of a new mode actuator on the net to see this plate.

Chances are that a plastic gear inside your mode actuator has split. I found a replacement gear on Ebay. Replacing the gear is another task.

Having the title's air flow problem with my '99 (2000?) BPA, and experiencing a reluctance from my B-dealer to repair it, I thought, what the heck, I'll google it to see what insights I may be able to acquire from the web for a possible DIY project by a non-mechanic retired engineer (me). So finding this forum quickly, I was amazed and educated by a page full of really helpful comments, altho it all sounds pretty complicated and not likely a DIY candidate! :frown:



That said, I'll get to my (now revised) point. As a 20 yr owner w/only 74Kmi on my PA, that considering my soCal environment I really don't need all those variable directional settings...and come to think of it, I'd actually be happier to jury-rig a 'fix' that would just freeze the system permanently to the dashboard-only flow, which if doable, would also likely be a lot less expensive than repairing to a factory performance which I don't need (or want) anyway. :smokin:



So that's it...I didn't see any post suggesting that option, so what say you guys? Anyone think it's feasible or not? :)

It is possible to position the actuator(s) wherever you desire. Then any actuator(s) can be disabled by unplugging the electrical connector to each actuator. The control head may flash the temperature indication as a signal of a system error, but it could achieve your goal.

As I had hoped, Blue Bowtie, your approach sounds relatively straightforward to implement. I'll pass on your suggestion to my next week's recommended repair garage to hopefully verify that it will work.



Thank you for posting so promptly! :smile:

Unfortunately, my 35-yr experienced and trustworthy repair guy reported back to me that he had tried your suggestion, but found that the GM designers - in case of failure - had designed the system to default to the window unfreeze position...which probably makes sense for a colder climate, but not for soCal.

So I'm stuck with either living with the window flow for hopefully several years yet, or biting the extensive labor costs of removing and replacing the dash in order to replace the dead actuator. Since I can afford it, and my PA has only my 74K miles on it, I've chosen the latter. :frown:

But thanks anyway for suggesting a solution which, except for the default design, should have worked. c'est la vie!