Well I'm having actuator problems on my 2004 Coupe. Throwing codes, blowing warmer air out of the passenger side, and vacuum leaks. I figured if I'm going to tear out the dash I might as well take care of everything. My question is how many actuators are in there? I know theres a right and a left but are there any others? Are they all the same? I just want to know so I can order all of them and change all while I'm in there. By the way I had the freon checked and it's fine with no leaks. I've done the fuse 27 trick and it's hit or miss. Driver side blows cold. Passenger side does not blow hot I gues you can say it blows neutral. Also the passenger side temp will not change at all when the dial is rotated.

 

There's 2. I'm skinny an have long arms and was able to swap them without pulling the dash, but it is easier that way. And the dash isn't that bad to do, at least in my Vert.

Vacuum leaks are what I'd address first. Get that all working. The path is from the back of the intake into the wiring harness, down below the battery and into the fender well on the passengers side. There's some stuff mounted to the A pillar and likely all of it is brittle and cracked. There's a reservoir for vacuum, a vacuum brake, and a Tee or two. From there it goes back under the battery through the bulkhead and to the vacuum divider. That stuff is all cheap and easy (relatively) and should eliminate most of your mechanical issues.

From there, the actuators are fairly easy, just a tad expensive. They're a colossal ripoff. GM should be ashamed of themselves for that.

Grab some vacuum hose, some emissions tubing (real small stuff) and get the vacuum fixed first though.

 

The vacuum leak is coming from right behind the passenger air bag inside the cabin. I'm sure it's going to be the vacuum line broken or the connector isn't in all the way or not sealing. Are those 2 actuators the same part or are they different? I'd like your advice on this should I go OEM or aftermarket? I've seen some "blend door actuators" on Ebay for as low as $15 but I dont know how good that can be.

 

Imo, it's highly unlikely the leak is inside the cabin..

Both the same part.
Not sure I'd recommend used... Rock Auto ... . $100 each or so. 90 anyway.

 

Thanks for the info. Much appreciated. Yeah used is a no go these things are finicky enough when new. I've hunted the vacuum leak all over. Outside the car everythings nice and tight. Inside it can get noisy but heres the funny thing in the morning when the sun isn't out as strong there is no hissing. When I leave work that the car has been sitting out in the hot sun all day it hisses like crazy and will go away if I cycle the modes on the a/c. Now if the temperature isn't so hot like on a cloudy day I get no hiss. Its weird but if you open the glove compartment the hiss is right there in front and above. Around the air bag area. I'll call the dealer tomorrow to see what the actuators will run me OEM I work at a shop so I think we get 25% off on GM. Thanks again!

 

Here's the thing. Once the vacuum leaves the back of the intake, it goes into that black hard plastic emissions tubing. That stuff gets brittle when exposed to sunlight, chemicals, battery acid, whatever. Shortly after leaving the intake, it enters the wiring harness and travels inside there down under the battery. What's under the battery will get brittle even inside the harness cover. But the rest will stay just like new. Same goes for what's under the dash. There's a big wiring bundle that passes into the passenger compartment right near the battery tray and frame rail. That stuff will be brittle as can be right till that bulkhead opening, and what's inside will be flexible like new.

Same goes for all that stuff mounted to the right side A pillar. All that stuff will have cracks and broken fittings. I can't imagine there's good vacuum all the way to the passengers compartment and THEN it is broke. Just not buy'n it. I'd be more inclined to believe you're hearing something on the other side of the firewall. Maybe close by, but other side. If I'm wrong... then somebody had to have already replaced all the rest of the tubing and quit a few feet too early.

To make that passage, I was able to cut a piece of that hard plastic tubing on a sharp angle, then push it through inside the wiring harness. You can pull out the old stuff first and give yourself a little more room inside the jacket. But it was pretty easy.

Even at 25% off I wouldn't bother with GM. They already have one chance to make a decent actuator, and they blew it.

 

Moved to C5 Tech.

 

I see your point and I will dig deeper into the intake vaccum under the battery in the harness. You sound like you know what you are talking about so I will take your advice. I just wish you could hear it. The leak it's so clear and pronounced like it's in the cabin with you. By the way dealer quoted me at $159 each actuator. You think I should go with an aftermarket like Rockauto or Dorman? Sorry for picking your brain so much but you've been very helpful. I just want the best quality part whoever makes it.

 

The thing is, the ones for $90 or not aftermarket. They're the same ones you're going to get from GM. GM hasn't made these things in a millennium. Well, GM never did but they've not had a factory spect one in years. Just go to RockAuto.

When I did my C5 I ran a separate rubber hose from the back of the intake Down Under the battery. Reason being is I could not get the emissions tubing to travel inside the wiring harness and just wasn't worth it to deal with that. So that part of the trip was made outside the wiring harness wrap. From there though, I followed the factory path and The Passage through the firewall is really short so that's easy to do just pushing the emissions tubing through.

It's easy enough to check if you have a leak at any of those points because it's really just a straight shot. In a pinch you can just suck on the line and plug the other end and if air comes through you know something is wrong.

All the stuff under the dash to be perfectly honest is easy to look at without touching a single thing. That's all exposed. Once it comes through the firewall oh, you will see that black emissions tubing plain as day going all the way to that Junction block or whatever you want to call that distribution thing, you've got vacuum coming to that point. That block simply doesn't leak. And everything from there on it's just vacuum Dash parts and I hate to say they never fail but I've never heard of one failing. Okay? So I'm just playing the odds here and I'm saying that there's no reason for me to believe the vacuum leaks are inside. That would be the easiest place to fix. The rest of it is either behind the intake or in that damn fender well and those are not nearly as fun. If somebody fixed something, you would like to think they took the low-hanging fruit.

 

I should also mention that the block you were talking about that you were thinking might have your leak. That's a block about 4 and 1/2 in wide by 1 inch by inch and a half. It's aluminum and you'll be able to see that underneath the passengers side of the dash if you lay in the footwell. The connections that go to that are two. There is the vacuum line that you're looking to diagnose. And then there is this great big block of connections that's all molded together, it's made of some sort of silicone Rubber and it simply doesn't get brittle or fail. That's the other connection. So from there the odds of a leak is pretty damn unlikely. Pull out the floor mat and the cover panels in the footwell and you should have full access to everything inside the car. At least everything that matters.

 

There are ONLY TWO electric temperature control BLEND DOOR actuators. They are what control the passengers and drivers side blend doors/ temp. That is where the temp control comes from.

The VACUUM, ONLY controls the level dampers that direct the flow of the air through the HVAC Air Box. Defrost, upper vents, lower vents both upper and lower vents "BI LEVEL" and fresh air or recirculated air.

The vacuum line comes from the vacuum reservoir into the cabin through a wiring harness and goes to an electronic solenoid control valve. That valve is controlled by the HVAC Control Module. When you select DEFROST, the solenoid for the defrost opens and directs vacuum to a vacuum controlled damper servo piston and it moves a damper in the air box to allow air to flow out of the defrost vents and none of the other vents.

Each time that you select a mode of damper operation, the damper servo has to VENT and them vacuum is applied to a different servo dampener. IF, the hose for a specific servo is damaged, it will hiss when vacuum is applied. NOTE, All the servo hoses are a soft rubber hose (unlike the hard brittle vacuum line). The hiss can also come from a malfunction in the electronic solenoid control block that controls the vacuum routing for the air box.

EASY INSPECTION: Take the close out panel off for the passengers side and look at the servo control lines for the servos on that side of the air box.

Bill

Bill

 

I'm having the same problem except the passenger side blows cold ant the drivers side is neutral. I checked the codes and found 99HVAC has BO446 H C.
This code means right actuator is out of range yet its the right side that is blowing cool air. When I go through the modes on the control the zones all change and the recirc changes to fresh air as normal.
The other day I noticed the AC was kind of neutral on the drivers side so I gave the system a little bump of 134 with no change. The next day when I tried the system I got only very hot air. Outside temp was 97 in NorCal.
After checking the codes I reset all of them and the AC worked again as described earlier. ANY IDEAs what to do about it? I'm considering replacing the receiver drier as I doubt it has ever been replaced. It can only help overall but it should not do anything for the difference in zone air temps.
Thanks for any help you might have.
Edit. After carefully reading the previous posts I will look closer at the vacuum system and replace the blend actuators.

 

K-Spaz, on my C5 convertible I replaced the blend actuator on the drivers side and removed the glove compartment to access the actuator on the passenger side but there is an aluminum structure that the airbag is mounted on that is blocking access to it. Do I need to pull the entire dash just to get to the actuator? I cant tell if that aluminum structure is separate from the entire dash or not.

 

see my thread with pic's !!!https://www.corvetteforum.com/forums...-actuator.html

 

Sorry, missed this.

I'm going from memory here... It's been several years...

As I recall, the drivers side you can get from underneath (if you've a contortionist). The passengers side I'm almost sure you have to remove the dash. I think I've heard folks talk about doing it with the dash just raised up some, but not completely out. In a Vert, (mine was a vert), I would almost say just take it out, it's easier. Maybe on a coupe the room to get the dash out is less and leaving it in is easier. On a vert, I think it's best to just remove it. I know that's how I did mine. I do remember laying in the footwell reaching up to do the driver's side though.

The aluminum structure is absolutely separate from the dash. It's not even part that holds it up. It's there for the airbag. Can be sharp too, watch that.

 

Thanks for the reply. It looked to me that if the aluminum airbag support were removed the actuator could be accessed. Ill try to remove it and see where that gets me. I changed the drivers side with relative ease. The weird thing is that the drivers side is what is blowing warm air yet the codes say that the right side is out of range and there is an open feedback. ???
Cheers