VIPERBLUELX

The air blows out a little from all the vents at the same time. If you put it on Defrost, or vent or floor it changes on the screen but it still continues to blow out a little from all the vents. I haven't noticed really since I haven't had the car long, but today it was hot and the A/C doesn't do much good with 30% coming out the defrost. Any ideas?

jedblanks

Use DIC to pull HVAC codes.

Probably a broken plastic gear in HVAC actuator.

-or-

Have you had your intake manifold off recently?

Bill Curlee

You have lost the VACUUM CONTROL signal that the HVAC System uses to change the vent door positions. It comes off the back of the intake manifold through a small black nylon vacuum line, through the wiring harnesses and down to the passengers fender well. There it goes into a black plastic vacuum reservoir and then it goes through some Ts and a check valve to the A.I.R. System control valve and to the HVAC Controller.

Its TOUGH to see the fitting on the back of the manifold and almost IMPOSSIBLE to touch it! Hopefully that isn't the issue. The other possibility is your battery leaked acid and the acid ate up the nylon lines. Thats a BAD thing $$$$$$$$$$$$$$$$$

Check those vacuum lines.

Bill

neokorros

i have the same problem

madmatt9471

After a careful search and study in my Shp Manuals I found that on mine it comes out to be the: MODE Actuator.

It will need to be replaced, but I do suggest that you follow Bills advice and first check the Vacuum lines to make sure it is not those!

Pull the codes and it'll tell what you will be looking for!

More than likely it'll be a B0441 code I believe, with perhaps another one or two codes beginning with the B0****.

let us know what you get

Thanks,Matt

c5mtl

same problem here...but are the actuator not electric??I hear then opening and closing when i reset the codes....does the car need to be running to switch vents???Could someone try this ....try changing which vevt the air goes to with the car not running

LV,99LS1VERT

Are all lights on your climate control working these units go bad offen.If the vac lines are disconnected you would easily here air coming from the behind the intake manifold.Or under the battery,as acid may have eatting away the vac lines.

Bill Curlee

There are TWO active controlling systems in the HVAC Air Box. One of them is electric and is responsible for controlling the air temperature. There are two controllers if you have duel climate control and they look like this: (square/triangle thing)





When you reset the codes, those are the things that you hear cycling through their full ranges.

Heres what the insides look like:





The round cylinder with the brightly colored lines are the vacuum actuators that change the VENT positions ( defrost, upper vents, lower vents ect...)











The vacuum for the system comes from the back of the intake manifold through a very small nylon air line:



Here is what the 90 degree rubber nipple and line look like at the back of the manifold:





From there it runs through wiring harnesses and down into the passengers fender into the Vacuum reservoir:





The reservoir supplies vacuum for TWO things:

The A.I.R. Pump.
Th HVAC Vent door actuators.

If you disconnect the line from the intake manifold the leak is small enough that it wont make a lot of noise or effect the engine much.

You can check that connection with a mirror and a flashlight.

When you switch VENT positions, you can hear the vacuum bleeding off different actuators and pulling on the ones selected. The actuators are fairly large and the reservoir is small. The engine needs to be running to operate the vent controllers more than one or two positions.

BC

c5mtl

never had acid problem on my car ...luck i guess....dont know what to try next....i am on my second dual hvac controller with the same problems

NASAblue

I changed out my wheel speed sensors at the tune of $550 for new ones (my own time in labor), and that didn't solve my tcs problem.... As a matter of fact I can't do anything to solve that problem, I just learned to drive w/o abs or tcs and I'm a hell of a lot better for it......
But I sure would be faster with abs......

Point is, the module probably wont be the problem, it's the bs wireing and connectors......

you can change the parts all day long but if a harness somewhere say in the door is bad it f's the whole works......

I'm gutting my electrical system and running all my own home runs with GOOD copper wires that have more than 3 strands (32 gauge )when I put in a roll cage and take out the bose system.

Always props to Mr. Bill, the vacuum line thing is a good probability.....

c5mtl

does anybody have wiring schematics for the harness that plugs into the hvac controller....trying to figure out if thier is more than 1 wire for the immumination....i found 2 yellow wires one is for the dimmer the other i dont know

widewheel

Bill,
Excellent write up and especially great pics of the HVAC system.

VIPERBLUELX

My car doesn't have any codes in it

jedblanks

Then it almost has to the the line going to the Map sensor on the back of the intake. Provides vacuum for AC doors.

neokorros

had mine fixed yesterday. had to replace the vacuum lines under the battery (corroded) and replace the vacuum line to the back of intake manifold (pinched)

works awesome now

~ nick

VIPERBLUELX

I checked the line on the back of the intake and it was fine, but when I removed the battery I didn't see any lines under there, do I need to remove the battery tray also? Got any pics?

Bill Curlee

The vacuum lines enter the main wiring harnesses and are burried. Your going to need to untape the harness, fine and repair the lines and retape the harness.

Have you checked the lines at the vacuum resivour to see if you have vacuum to that point. Maybe the line is good and loose at the fittings there in the fender well.



Theres a fender access in the fender well...

VIPERBLUELX

I'll pull that access panel and check it hopefully tomorrow, thanks again.

OhioC5

So Im not alone, I noticed this on my car too. Thanks for the great info.

'VETTE PHASE

Is this it?