HVAC Gurus-Air only out denter vents!

[FFarr]

^CENTER VENTS..All thumbs.

As the title says, only get heat and cool from the center vent, no defrost or floor air. All other functions seem to work properly.
Has anyone had a similar problem?

As I have researched, four electronic actuators that control floor, dash vent and defrost ducting.

Can anyone that knows their way around these actuators lend a hand???

 

[84ZZ4]

There are four actuators, as far as I'm aware, but only one controls which set of vents is active.

As far as I know, they are:
1) Passenger's side temperature control
2) Driver's side temperate control
3) air source (outside air/recirculate) control
4) vent output (mode) control

I suspect that #3 and #4 are behind the glovebox, near the blower motor, but I'm not sure. #1 and #2 are mounted in the bottom of the center of the desh (about where your mid calf is on the inside of the car).

This image shows you where #1 and #3 are. #1 in my list is #5 on the drawing, #3 in my list is #2 on the drawing. #2 on my list is essentially in the same position on the other side of the car.

http://ww2.justanswer.com/uploads/GUYVANIDERSTINE/2011-10-30_053059_4.gif

I can't find a picture of the mode actuator (#4 in my list) for a Park Avenue. If no one else posts I can see if there's anything in my '98 service manual late tonight.

 

[FFarr]

I pulled the lower underdash panels, there is an actuator that controls the floor vent doors, some kind of plastic eccentric wheel attached. left center of the of the dash.
I can turn the wheel by hand and the floor vent doors will open. When I set the control to floor I can hear the actuator "click" and the wheel jumps but no other movement.
Is this the mode actuator?

 

[HotZ28]

Click Here for more info. BTW, there are four actuators shown & item #51 appears to be the mode actuator, but if the item is not shown in the parts listing, that means it is no longer available from the GM parts warehouse. However, you might get lucky and find a dealer who has one in stock. Good Luck.

 

[Spriteman]

I pulled the lower underdash panels, there is an actuator that controls the floor vent doors, some kind of plastic eccentric wheel attached. left center of the of the dash.
I can turn the wheel by hand and the floor vent doors will open. When I set the control to floor I can hear the actuator "click" and the wheel jumps but no other movement.
Is this the mode actuator?

Yes - that is the Mode Actuator - towards the seats will be the driver side temp actuator. The mode actuator is hard to find replacements for - I've found 1 at the local salvage yard for $50. I had seen one on Amazon and Ebay but I am having a hard time finding it again on either site. I was able to find the GM part # and then I just did a Google search for it and it popped up in a couple of places. I'll see if I can track that down again.

The inside of the actuator motor/nylon gear gets ground down causing it not to be able to turn the linkage that you were able to turn by hand. If you want to just pull the electric connector and turn the linkage by hand to where you mostly want it to be used - i.e. heater in the winter

That will at least give you some heat and some time to find another one for replacement.

 

[Spriteman]

Ok - just talked to my local Buick dealer and the answer is a little strange. He says that you can order the blend door and air inlet actuators individually but when ordering the mode door actuator you have to order the bracket it attaches to and the actuator comes with it - the GM part number for the bracket is 89018383 and here's a link to it online - http://parts.nalleygmc.com/showAssembly.aspx?ukey_assembly=368150&ukey_product=3105096

The bracket is #53 in the diagram and you can see that the mode actuator is #51.

I was surprised that it was only $83. It looks like it would take a lot more work to get that whole bracket assembly out from underneath the dash. I guess you could just order the bracket and remove the actuator from it and replace the bad actuator.

Hope this helps.

 

[FFarr]

This is an awesome help forum. Thanks guys for the information.
And special thanks Spriteman for providing part numbers and calling the dealer.

 

[FFarr]

Ordered the HVAC bracket (along with exhaust hangers) from GMpartsgiant.com. Doing stretching exercises daily for a day under the dash! 😉

 

[Spriteman]

You might want to do your exercises inverted because that's the best way to get at those areas.

 

[FFarr]

Got the new mode actuator and removed the old;

Took the cover off the broken actuator and found this;

Larger blue gear is broken allowing the hub to not turn.

Wow, what a job. Spent the afternoon on my back under the dash. Had to holesaw a access hole in the dash (will be hidden) to access one of the screws.

 

[Spriteman]

Congrats on getting that job done - it's amazing that just a little nylon gear can hose up the A/C.

 

[HotZ28]

Very common failure! It seems that GM loves plastic gears & the only thing different from the previous year failures, was the color of the PLASTIC gears. GM should be required to replace under warranty, and send all the failures back to China for free replacements. This pic was from a 1995 actuator.

 

[Kevandkaye]

Same thing happened in my '06 chevy truck and may be happening now in my P.A. How do they escape accountability for this cheap crap? Not much different from the cheap-ass seat gears they use.... I still love the GM's though! Mine never seem to have MAJOR isssues!

 

[Maylar]

I hope those things are still available - I'm dropping off my PA to the dealer for exactly the same thing tomorrow. He quoted me 4.5 hrs labor... ouch.

 

[HotZ28]

I hope those things are still available - I'm dropping off my PA to the dealer for exactly the same thing tomorrow. He quoted me 4.5 hrs labor... ouch.

They are still available. Read post #6 for more info. (And special thanks Spriteman for providing part numbers and calling the dealer.)

 

[FFarr]

Heater works great now, able to get air flow from floor, center vents and/or windshield. Installing the mode actuator is a b*%^h, three bolts are relatively easy with a 5/32" socket and a universal (1/4" drive) but one bolt is impossible to access. Had to use a 2" holesaw through the aluminum dash casting to gain access to the last bolt. Lower dash must be removed and when re-installed will cover the 2" access hole.

The FSM is useless when replacing this actuator, says something like find actuator, remove wires, remove bolts, reverse for reassembly.

Cabin air filter was totally plugged.

And thanks guys for the assistance. Having this forum is 10x better than the FSM.

 

[Enslow]

I read once that disconnecting the battery before turning the HVAC system off can cause that gear to split. I don't know how true that is, but it wouldn't surprise me. I now try to remember to shut the system off before I turn the car off.

 

[Spriteman]

So FFarr - which job was worse - replacing the actuator or putting the new 3 piece cabin air filter in? When I replaced my filter I had to be put in traction for 2 weeks - okay, not really, but it's a major PITA.

Did you wind up removing the new actuator from the new bracket and just dealing with the actuator replacement?

 

[FFarr]

So FFarr - which job was worse - replacing the actuator or putting the new 3 piece cabin air filter in? When I replaced my filter I had to be put in traction for 2 weeks - okay, not really, but it's a major PITA.

The actuator. Wouldn't be near the chore if I ever do it again but it was a pretty difficult job.
Three piece? I just found one piece. The part I removed was approx. 10 x 3", it was so clogged with crap I pulled the "tangs" off that are used to pull the filter out. Made a L shaped hook with a coat hanger that allowed me to fish the filter out.

Did you wind up removing the new actuator from the new bracket and just dealing with the actuator replacement?

The bracket is sandwiched between the actuator and eccentric wheel. The eccentric was bonded to the actuator shaft so I was afraid to seperate the actuator from the eccentric wheel.

 

[Spriteman]

Well - in my 1998 there are actually three of those 3 x 10 filters that slide together to make up one larger 9 x 10 filter that covers the evaporator. I did find that the bottom one - which is the one you pulled out - is the dirtiest.

Did you buy a new one? Check out this page - http://www.autozone.com/autozone/parts/Cabin-Air-Filter/_/N-8gdaf?filterByKeyWord=cabin+air+filter&fromString=search - does the bottom section look like yours?

I hate to be the bearer of bad news but I'm guessing that the other two are still up above in the evap box. Mine slid down fairly easily once the one below was out. You have to remove each one of the three sections one at a time.

Don't buy the Fram filter - piece of crap from China fell apart within two seconds of trying to get that sucker in there.

If you wind up wanting to replace the other two sections let me know - there are a couple of tricks to make the process way more painless.


I think one of the other guys said that the NAPA part was a good one - http://www.napaonline.com/Catalog/CatalogItemDetail.aspx/Cabin-Air-Filter/_/R-FIL4874_0066957339

PS Make sure you note how it looks when you're pulling the other two sections out - once you've got them out it gets a little backwards on putting the new ones in - just remember that the tabs go on top and the grove goes on the bottom and the flip out pieces go toward the opening.

Another note - after you get them all out get your shopvac out and put it up to the opening where the filters came out - I had a mess of leaves and dust up in there. I actually went underneath the hood and took off my wipers, the screen covering the area below, and vacuumed down there as well - it's supposed to clean out when it rains through a couple of rubber drain flaps on each side under the screen but when you get too many leaves and you start going down the road at 70 mph I guess anything in that area can be blown around and wind up in the evap box.

I even drove around on the highway a couple of days without the new filters in yet just to let the wind help push any remaining dirt/debris out the open access panel on the inside. Probably overkill - but I feel better knowing it's really clean.