Write-Up: HVAC Assembly

Jack the R wrote:

By re-run calibration, do you mean you already did it?  it wouldn't hurt to try again.  Are you sure you have the right instructions for the calibration procedure?

I don't remember there being any special tricks to installing the modules.  I don't have one on hand, doesn't the output shaft have a half-moon design so it only goes on one way?  

Surely you couldn't have flipped the actuator door over?

Thanks! I think I just needed a nudge. I'm kinda sore from the initial install...

I will try recalibrating and before that checking this site for the calibration procedure. I had done it before, did it this time from memory and I'll bet I screwed it up. Last time I installed any driver side actuators was July 2013. The output shaft goes on one way, sort of, it's more or less oval with the long sides flat.

Thanks!

Albert

I ran calibration this morning and things are, well, great!

I must have been sleepy or fatigued when I did (ummm... when I screwed up)  the initial calibration right after installing those actuators.

Albertj

Good to hear!

Albertj good news did u take the seat out? How did you do calibration I just left key on for 3 minutes

Hi Steve (and the rest of you),

I did not remove the seat.  I put a small stool just outside the door opening, rested on that and the footwell.  Small of my back just cleared the door sill.

The calibration - With the car running I turned the HVAC to "OFF" and then shut down, disconnected the battery again, grounded the positive terminal for about a minute then went to make/eat dinner (left the terminal hanging).  After dinner (chicken) I reconnected battery, turned the car on (did not start it) and let it sit HVAC off  while listening for actuator action. It was hard to hear - the new actuators (aftermarket, not OE) are really quiet for some reason - and it took 3-4 minutes.     Then I turned car off, waited 30 seconds, started it, took a drive. Once the car was warm enough (temp gauge about 1/4 up) I tried the different settings -- no THUMP and everything seemed to work (winner, winner, chicken dinner).

I figure the first time I did something dumb like forgetting to turn the HVAC "OFF."

Albertj

Thanks Albertj great info! Thats a fun job and your neck and back really enjoy it too

71stagegs wrote:

Thanks Albertj great info! Thats a fun job and your neck and back really enjoy it too

I've looked at 3, and as far as my eyes can tell it isn't moving - but there are two doors near it which are moving.  The upper door may be a little hesitant sometimes.  Going by the description, 3 seems like the most likely culprit.  I'm sure you guys have seen this problem before.

edit - May have already found the answer -

99Rivman wrote:

To get to the passenger side actuator you remove the glove compartment and it is right there on the side of the HVAC Module. Mine just seemed to be stuck in one position, I opened it up and put voltage directly to the motor and got it moving and it has worked ever since. I used a battery holder from Radio Shack, three AAA batteries that made 4.5 volts and it did the trick for me.

Link

Will welcome another opinion before I fork out $ for a new module.

Remove and inspect the old servo. Most likely you just need the big gear which is about $15 on amason or fleaBay.

Well that'd be nice

Jack the R wrote:

Well that'd be nice

I've worked on my heater box twice while I've owned the car.  The servos will work broken to an extent, until the big gears crack in more than one place or bind and lose teeth.  

Back when GM went to electric servos from vacuum (not on all models) they put in metal gears.  Those suckers about never broke.  The first time I servied the heater box I pulled all the servos because the thing wasn't working consistently and sometimes you could hear them "hunt." I replaced the bad ones with junkyard servos to the extent I could get them, and I think I got one from the local GM dealer.  

This time I pulled and overhauled or replaced all the servos. Some worked and a couple (defrost blend and passenger temp) didn't. Pulling and checking them (an ordeal) I found they *all* had cracked gears.  I had some servos from the junkyard trip (they sell them cheap at the regional pick-n-pulls) and opened/checked all of them.  Woo Hoo!  They were all good and some had the old metal gears. I made up working servos with good gears from teh parts I have and I also four via Amazon to make up the rest, they are not OEM though (I will explain).  The junkyard ones that would bolt in and had metal gears I checked with a 9V battery and I think one I used and one I scavenged because the motor seemed weak.  

So - at the end of the day so to speak I installed all four of the Amazon-sourced servos I bought and all the ones I'd overhauled.  One of these and three of these. The replcaement servos from the Amazon sellers are somewhat different inside compared to the OEMs but function fine. They are quieter than the OEMs and the motors are a little smaller I think. They had some mostly good but some bad reviews on Amazon.

I surmise that the issue is that if anything is wrong or ever goes wrong with the blend doors the replacement servos will break instead of attempting to reset themselves as the OEMs do. My further guess is that, as it is, the replacement servos' torque is adequate to move the doors and that's about all. The OEM servos are much more robust in operation. Where I am going with this is just that I suspect GM used the same servos in a number of different cars. The heaterboxes differ car model to model. So I guess depending on which heater box you're bolting the suckers onto the replacement servos may not work so well or may not work at all because the boxes differ significantly in terms of how much those doors weigh. I seriously doubt that is a problem on the Riv, as I can manipulate all my heater box's doors with my fingers on those little axles if the servos are removed.

What you might want to do is get some junkyard servos, preferably older ones out of 90s SUburbans if you can find them, they are as likely as not to have the metal gears. Maybe get 3-4 of the Amazon'sourced ones too. Then take a half day, pull the servos on one side and open them to see how bad the problem really is (or isn't). Then either fix or replace the servos with parts on hand. The guts of the replacement servos are not really swappable with the guts of the OEM servos. Point is, though, if you do it like that (which in retrospect is roughly is what I did), it's a once-in-a decade job because the clock so to speak starts fresh when you have all good servos.

I'll be thrilled if I can find the time to get this one servo working again.

Jack the R wrote:

I'll be thrilled if I can find the time to get this one servo working again.

Once you get stuff out of the way to get to it, it's not too bad. I used an inexpensive 1/4 inch ratchet wrench set from Walmart. You might need an extra extension. I put a stool just outside the drivers door (cash me ousside he he) and laid in the footwell, and I did not detach the lower heat duct just unclipped what I could reach of ti and bent it out of the way.

I've got the tools, but time is at a premium.

If only I could order a bunch of metal gears . . .

Jack the R wrote:

I've got the tools, but time is at a premium.

If only I could order a bunch of metal gears . . .

The reason to find old GM cars in the junkyard is to snag metal gears for this application. So -- If you want to teardown modules and scavenge gears, 1988 or later Chevy trucks are where to look (modules are easy to get to), and generally on the MY 2000 and later ones (well, thru 2014) they are electrically compatible too. Again, most yards have a Hollander or similar guide book and will tell you what cars/trucks to pull modules from. The low-line Chevy pickups are just easier to pull from because there's (much) fewer parts in the way.

Metal gears were available, I have not seen any of late (couple years). McMaster Carr sells gear stock, but you'd have to finish the machining yourself (basically drilling a hole exactly in the middle for the axle). There are molded and 3-d printed plastic gears readily available from eBay and Amazon.

As long as we're on the subject I get cold air on the driver's side all the time and it feels as though it could be conditioned air it is so cold. I was thinking #4 is the issue but perhaps #5? Otherwise, everything works as it should. As always, Thanks!

Ken,
If passenger side is working properly then I would focus on the drivers side blend door or air mix door. If it is inop in the "COLD" position then I would say focus on #5 by adjusting the temps and watching, feeling the motor to see if its moving.
They are relatively easy to replace.
Good luck and let us know what you find out.

So, Wizard....

How do you get that lower duct off? I don't get air out the vents on my feet, so I need to change the AC Door (mode) actuator.

Any tips? Or do I just start going at it?

I have the stock actuators in mine so I have never had to do that. Let us know how you make out.

damn. ok. I'll do what I can and report back. Not looking forward to this.

96 bux. dayum. I guess I'm just happy we can get the damn thing.

Yardley I changed all of mine put Delco's in. In a year 2 went bad I got 4 seasons brand for $44 SOB same as Delco same numbers all made in china junk got them at rock auto It is a tuff job getting under there i took my seat out then u can lay out and get your head under the dash. the seat has 2 bolts in the back hooks in the front comes right out a few plugs under the back of the seat .U will feel like Mr Pretzel when u r done Good Luck

So, I don't get air blowing out of the floor vents. I'm thinking actuator #3 in the front? Can anyone confirm before I start tearing into this thing?

No air at all? There isn't a large volume of air coming out the bottom of the Riviera.

Yardley wrote:

So, I don't get air blowing out of the floor vents. I'm thinking actuator #3 in the front? Can anyone confirm before I start tearing into this thing?

Regarding tearing into the HVAC actuators.

The working space is TIGHT but you can do it by removing the panels under the dash (driver and passenger) and regarding the lower heat duct on the drivers side, I did not detach the lower heat duct just unclipped what I could reach of it and bent it (actually nudged it, no broken bits and no new creases) out of the way.

You need to look in the service manual to see which servo does what. Alternatively what you can then do is turn on the HVAC (reconnect battery and turn key to ACC I think, if that does not do it turn key ON) and push the different buttons on the HVAC head to see which servos move in response. If the car is cold, some flaps won't move because the HVAC head is set up not to turn on the heat until it warms up. Which servo is which isn't all that obvious from observing their positions on the air box unless you've worked on other GM HVAC, and working upside down doesn't help (me).

Only other thing is if you look back up this thread you might see a comment from me about installing aftermarket actuators I got from Amazon.com, they are "AA Ignition" brand and all working fine so far. Only complaint so far is they are very, very quiet and I had a little difficulty initializing them (i did not follow the service manual instructions right the first time).