ncali

My Ac worked beautifully until the first 100 degree day . The left side started blowing hot , right side was a bit cool for a minute then
it started blowing as if the heater was on . I crawled into the passenger side floor space with the engine running and under the center of the dash I can hear a pretty good vacuum leak on the right side
I havnt taken it apart yet but I wanted to ask what the vacuum actuators open , and what the electric actuators open ?
using the MODE button on my dual control the air will change to the proper position

K-Spaz

The blend doors are all electric, doesn't matter if you have dual-zone or manual AC. The vacuum operated doors are the big ones that determine if you're using heat or AC. I forget how many vacuum dashpots there are but I think there are four. There's a distribution block if you look under the dash at the passenger side. The vacuum sources that comes from the passengers Fender right in front of the door and from there goes to the back of the intake. There are some tees and check valves and a vacuum Reservoir behind the fender. The vacuum line to and from there is an emissions hose that's hard plastic line and gets brittle. I would check that first. It is small and it runs inside the wiring harness from the center of the cowl down to the fender and then back out underneath the battery and through a bulkhead connector into the passenger compartment.

jjc508520

On mine - I get AC out the dash vents but not out of the floor - this is a blend door issue?

K-Spaz

No. Blend doors control output temp. The vacuum operated doors control the path/destination.

Bill Curlee

The vacuum actuators control the door dampeners that make the air come out of selected vents CENTER HIGH, FLOOR, DEFROST etc..

The electric actuators control the temps. and select between heat and cold (heater core or AC evaporator or temped air between both) Feel the line coming off of the AC receiver dryer behind the battery If the receiver dryer canister and the line that exits the canister are very cold, the AC is cooling.

K-Spaz

I think that's what I said.

Bill Curlee

You are absolutely correct!!
I was at work and started to answer the post. Got called away for some BS work related crap and when I got back, I pressed the SEND button.. .You had already posted. Sorry

K-Spaz

No problem, I thought you were correcting me.

Many ideas don't come across well in text.

ncali

Feel the line coming off of the AC receiver dryer behind the battery If the receiver dryer canister and the line that exits the canister are very cold, the AC is cooling.

The receiver and the line are cold, I can hear a vacuum leak under the dash. When I connected my tech 2 I got no response from vacuum 2
it stayed off while the others I could switch on and off

ncali

I found this page on indexing the actuators and of course the pictures didnt post. Is this what I need to do?

Preface :

B0441 and B0361 HVAC codes

Hot air blowing out one or more vents is a common problem with 1997 – 2000 Corvette C5’s. If you feel like you are being baked in your car, and your passenger is nice and cool, more than likely you have an incorrectly calibrated HVAC actuator. The best description I have found isn’t from any C5 TSB, but from a Buick TSB :

Condition
Some customers may comment on a temperature variation between the left and right hand ducts. Typical concerns may include that the right side of the vehicle cools down but the left stays warm or the opposite. This condition is sometimes associated by the customer with a recent service visit for other non-related repairs. The codes, DTC B0361 or B0441, may be present but will not illuminate a telltale lamp.

Cause
The HVAC controller unit and the TEMP door actuator motors rely on a feedback system that supplies the controller with count values in order to accurately adjust the air temperature. When battery power is interrupted to the HVAC controller, the current actuator position values are lost. When power is restored, the controller will perform a "sweep test" of the doors from full cold to full hot and record the end values for reference. Over time, the TEMP doors may develop some flexing when run to their extremes. This flexing allows the count values to run out of range (beyond 0-255) and results in DTC code B0361 or B0441 to set.

Correction
A revised HVAC controller has been released with new programming that allows for a wider tolerance in the expected range of the TEMP door. Replace the controller.

My experience for the last 2 years has been this. About 50% of the time, when power to the HVAC system was interrupted, or a PCM reboot occurred, I would encounter the above problem. For me it was whenever I disconnected the battery for service, or when I reprogrammed my PCM using EFILive. As part of the reprogramming process, EFILive would perform a PCM reboot. It was at that point the HVAC system would go through the HVAC door recalibration as described above. About half the time it would fail, throwing the B0361 and B0441 codes. Removing the battery cable most the time would cure it, until next time I reprogrammed the PCM, or disconnected the battery for any reason. It might be worthwhile disconnecting your battery for a few minutes. While it will probably come back at some point, this *might* be a permanent fix for your situation.

It is my understanding that this can be cured one of two ways. The first is the simplest, but most expensive way. A newer 2001+ HVAC head unit will supposedly cure it. As shown above, Buick also has a similar fix. The second (and documented below) is to reindex the door in question. The document below is ONLY for the driver side Actuator. This seems to be the most common one to fail. If you are not getting codes B0441 or B0361, stop reading! It’s either the right Actuator, or possibly some other HVAC issue.

Important : If you are getting B0441 and B0361, adding Freon will NOT fix your problem!!!! I have seen several recommendations to add Freon as a fix. These codes have NOTHING at all to do with Freon!!!

1. Before you go any further, confirm that you have a HVAC DTC set.

2. Turn the ignition to ON (no need to start the car).

3. Press and hold down Options, and hit Fuel 4 times. This will put you into diagnostic mode.

4. The computer will now scroll through all the modules, showing the error codes. Once it is done it will display "No More Codes" At any time you can scroll up and down to see each code by using the Trip and the Options buttons. Scroll to the component that has the code and press the Gauges button to view the code(s) numbers. To scroll through these code numbers, use the Trip and Options button again. Hold "Reset" to clear any codes. You can delete one code at time or all codes in any component.

Using the above steps, you can confirm that there are indeed HVAC codes set. If you have never done the above, now would be a good time to make note of any other codes you might have.

Before you go any further, scroll until you get the HVAC using the Trip or Option button. With 99-HVAC highlighted, press and hold clear. You should hear the HVAC doors going through their recalibration. Wait about 15 seconds, and go back through all the codes. If HVAC is now clear, you might want to hold off on going through this document. Chances are though the B0441 and B0361 codes came right back. If so, I would recommend the recalibration of the driver side actuator.

[img]file:///C:/Users/owner/AppData/Local/Temp/msohtmlclip1/01/clip_image002.jpg[/img][img]file:///C:/Users/owner/AppData/Local/Temp/msohtmlclip1/01/clip_image004.jpg[/img]


Pictured above are the HVAC codes you should see. Stop if you do not see these codes!



[img]file:///C:/Users/owner/AppData/Local/Temp/msohtmlclip1/01/clip_image006.jpg[/img]




There are 2 ways to get to the drivers side actuator. This is NOT the method documented in the GM service manual, which recommends pulling the instrument cluster. It’s possible the GM method might be easier. I went this route. While it’s possible to ‘get to’ the actuator with only removing the kick panel cover (the one with the light), you won’t be able to remove it with the HVAC sensor baffle in place. This requires removing the lower dash pad, basically in the same manner as you would do the Column Lock Bypass. Once that panel is removed, you can move the sensor airtube out just enough to remove the baffle. Since I have only done this once, and hope to never do it again, I can’t say for sure if you can do this with only removing the one kick panel. It would be worth a shot to try this first as that panel has to come off regardless.

Before you start, disconnect the battery.

[img]file:///C:/Users/owner/AppData/Local/Temp/msohtmlclip1/01/clip_image007.jpg[/img]Center Console Disassembly
1. All we are doing in these steps is moving the center console back about an inch.

2. Pry off the foglight/hatch release cover. Insert small blade screwdriver under hatch release, and pry outward.

3. Disconnect the wiring harness.

4. Pry off the HVAC sensor cover. Behind here you *should* find your temperature sensor.

5. Remove the torx T15 screws from the HVAC sensor area, and the foglight area.

6. Remove the T15 screws from the lower kick panel.

7. Open center console.

8. Remove the 2 rear bolt hole covers.


[img]file:///C:/Users/owner/AppData/Local/Temp/msohtmlclip1/01/clip_image008.jpg[/img]




Remove the 2 10mm nuts.









[img]file:///C:/Users/owner/AppData/Local/Temp/msohtmlclip1/01/clip_image009.jpg[/img]
Gently pry open the traction control cover from the rear facing side. Disconnect harness and set assemble aside



Remove the 2 screws in the cigarette lighter area. You will have to remove the ashtray to get to the second screw.

[img]file:///C:/Users/owner/AppData/Local/Temp/msohtmlclip1/01/clip_image010.jpg[/img]Slide the back portion of the console back, and then lift up and over the studs so you can slide it back another inch or so.
This will give you room to work around the ignition and temp sensor area.

Slide the front portion of the console back console, while releasing the clips surrounding the radio/HVAC. Once again, lift up and over the studs to give you that extra inch of working space.

Knee Panel Removal

See this page for better pictures and documentation on how to remove the knee panel :

http://www.ls1howto.com/index.php?article=24

[img]file:///C:/Users/owner/AppData/Local/Temp/msohtmlclip1/01/clip_image011.jpg[/img]From the bottom, pull down and back on the kick panel cover. It's in there!
On the top left portion of the kick panel (where the foglight switch was), pull out towards the back of the car.

On the right, pull out. Be careful not to yank the wire (sensor)! You will need to rotate the sensor to remove it, or remove the wiring harness from the sensor.

Remove the kick panel cover under the dash. (2 screws and a retainer)

While this step isn't needed, it really helps open up the work area under the dash. Skip it for now if you want.

Remove the metal/foam knee brace. It’s held in by 4 screws. Be careful with the HVAC sensor!

You will need to remove 2 wiring harnesses that will be attached to this brace

[img]file:///C:/Users/owner/AppData/Local/Temp/msohtmlclip1/01/clip_image013.jpg[/img]Actuator Removal


There is a air tube that connects to the opening where the HVAC sensor is located. You will need to move that whole tube towards the back of the car about an inch. It is 'locked' in place at the front of the tube, so you will need some small needle nose pliers to release it.

You can now remove the baffle. Shown is the GM drawing of this tube since I didn’t get a good picture

[img]file:///C:/Users/owner/AppData/Local/Temp/msohtmlclip1/01/clip_image015.jpg[/img]The actuator is behind the radio, on the side of the airbox.
It’s the black box above that has the barcode on it. There will be 2 small screws holding it in place.

[img]file:///C:/Users/owner/AppData/Local/Temp/msohtmlclip1/01/clip_image017.jpg[/img]I had to remove 1 screw from the BOSE unit - The metal box with BOSE written on it, not the radio.




The actuator removed!



[img]file:///C:/Users/owner/AppData/Local/Temp/msohtmlclip1/01/clip_image019.jpg[/img]


CAREFULLY remove the 4 screws and cover.

Gently pry the cover off slowly as not to disturb the current gear positions.


[img]file:///C:/Users/owner/AppData/Local/Temp/msohtmlclip1/01/clip_image021.jpg[/img]Mark the position of the gears, particularly the drive gear, and the small blue gear attached to the sensor.
Pull the center gear out top-most (no need to mark it) and pull the drive gear up. Rotate the big drive gear counter-clockwise 2 teeth. Disclaimer – After seeing someone else rotate this gear counter-clockwise and it worked, I also tried the same thing. It also worked for me. I make no guarantees that counter-clockwise is the correct direction for your situation.

Pictured is the mark I made on the big drive gear, and the blue sensor gear

At this point, I would recommend ONLY reinstalling the actuator. Reconnect the battery and see if the codes come back. I would scroll through to 99-HVAC on the DIC and press and hold the RESET button to force a reset of the HVAC system. See if that makes the code come back. Turn the HVAC ***** to both extremes (hot and cold) and check the codes again.

I even went so far as to disconnect the battery for a few minutes, a few additional times to confirm that the codes didn’t come back…something that was a crap shoot before I reindexed the actuator. If you are unable to get the codes to come back, you *should* be good to go ahead and put everything back together.

ncali

I defiantly hear a vacuum leak under the center right side of the dash. so I am getting vac through the manifold