scubaman15

O(K armed with this info I dug into the problem this afternoon . FiXED IT YEA its now blowing like a cheep hooker ... it was rotted pretty good caused by the battery lucky I found it before any of the wires were ate up ..I took three or four quarts of warm water with baking soda ..and cleaned up the whole area ..then inspected ,two of the vacuum lines were affected and I replaced both and tested its working again !!!!!!!!!!! Thanks all of you !!!! Man its tight in there , Its no wonder many take the car to a stealer . ... I had a bit of time with the door locks and radio after doing this repair, I feel I dodged a huge problem ..if this had been left to eat my wires ...dam don't know what I would have done !!! Thanks again .. I now have a perfect LOW mile C5 FRC for the price of Toyota econo Box !!!:chee rs:

danm2000

Great post and awesome information. I had the same problem and with your help was able to fix my problem!!! I have a 2000 coupe with 20,000 miles and did not think this would be the problem but it was. As I started to take the access panel off I noticed acid stains on the floorboard and frame.
I thought I may add a couple of side notes that may or may not have been mentioneed for other people when troubleshooting this issue. This is just to add more detail to a great post!!!
1) When you remove the access panel behind the passenger wheel, you will not see really anything because the contole module is right there. You will need to go under the car and look up behind the control module or pry the bottom fender away from the body a little bit with your hand and look upwards and you will see the vaccum lines talked about inthe pictures.
2) Remove the battery, then remove the battery tray with the 4 bolts in the middle of the battery tray (they are located in a tunnel right under the battery tray. When the bokts are removed you basically wiggle the battery tray back and forth and pull straight up. After removing the battery tray you will see the extent of the damage from the battery acid. You may also see the places the vaccum lines have been damaged.
3) My bad vaccum line on my car was the one that came from the "Y" connection at the bottom of the car and went up to the passenger kick panel inside the car. I traced the line and had 3 places where the acid ate thru the hard plastic vaccum line. I decided to cut the vaccum line with about 2" at the base of the connection and at the other end about 2" away from the connection. There were 3 different places where the acid ate thru the hard plastic vaccum line. I then went up to my local auto parts store and purchased a foot of vaccum line hose (rubber). Slid the hose over the bottom and top pigtails and everything worked.
4) I am going to purchase a battery tray mat so his does not hapen again.

Hope this helps.

64drvr

great write up!

Just to verify if I am having the same issue:
With the A/C on, it usually will not get any colder than just fans. Also, there is no audible or physical difference when switching from outside air to inside air. Is this the same issue that you encountered?

madmatt9471

Extra information aleays helps

Great addition glad you got it fixed

Thanks,Matt

Red98VA

either you guys have small hands or I am doing things wrong. I have the same problem but mine came from a LS1 to LS6 IM swap. It was fine then....blowing everywhere but where I wanted it. I had a hard time plugging it back in when I put the new IM on and figured that is where the issue was. I tried but can't seem to get my hand back there to see if it is off, and don't want to go through the hassle of removing the IM again. Any suggestions?

madmatt9471

Hey RED not small hands here but I do have small wrists! At time I have had Tina (My wife) take her small hands and reach something for me on the Vette.

Try to get a friend who may be able to reach back in there while you supervise

Thanks,Matt

Red98VA

sounds like a plan.

av8rdavid

I worked on this project today but was not successful...I yanked the battery and saw there was a little piece of rigid tubing that went to the right fender from the passenger footwell which was cut.
After removing the wheel well panel i reached in behind the PCM and found the check valve with the other piece of rigid tube coming from it.
I took a piece of silicone tubing and created a coupling to join the halves but not luck......Didn't get enough vacuum from the line so the HVAC doors are still not actuating.

I climbed under the dash, pulled the purple tube off of the black line, pumped vacuum into it and confirmed the switch works.

Can the check valve be bad?

On another note...Even though i have 39K miles and the car has anways been in the south, the amount of acid rust on the frame rails is frightening! looks like there is alot of battery drip going on behind the scenes here..

madmatt9471

Yes it is very possible the check valve can be bad! A check valve goes one way so by simply trying to pull vacuum back through on the opposite side of the check valve will let you know if it is working. IRemember it locks off, so it should hold vacuum if you try to pull it on the inlet side)

But I would pressume that there is another break in the "HARD" line somewhere, I would suggest that you run a whole "NEW" fresh piece from the check valve to the back of the manifold.

Try this and let us know! It certainly is worth the effort at this point!

Thanks,Matt

Wilzer

Have a 2005 C6, all vents are blowing. Does the C6 have the Vacuum line also?

Thanks

madmatt9471

TTT

Thanks,Matt

stevenhmiller

My AC works fine. When I flip on the heat, I don't get heat. No matter how I turn the dials, no heat. I'm getting codes B0361, B0363, B0446 and B0441. I can switch from upper vents to lower vents no problem. I'm wondering if this is also a vacuum issue or if I have to replace the actuators.

Any input is welcome.

madmatt9471

Then your actuators are out of whack - here is another write up another member did on how to RE-INDEX them:
http://forums.corvetteforum.com/c5-t...actuators.html

Another way I have delt with this is by clearing the codes with the Vette running and the AC or Heat dial set and running/blowing (You will feel it cyle back) and then shut the Vette off and then do a re-start and then turn on the AC/Heat and cycling between the two - the key for me has been to make sure I shut the Vette off after I clear the codes!

I usually experience this when I hook up HP Tuners and it cycles the PCM - This will happen with a handheld tuner too

Thanks,Matt

stevenhmiller

Madmatt - I tried the clearing the codes with the car running and ac/heat blowing, but no luck. I tried it with ac blowing, resetting and shutting down. Nothing. I tried it with heat blowing, resetting and shutting down. Nothing. I tried it with ac blowing, resetting, switching to heat, resetting, shutting down. Nothing. I tried it with heat blowing, resetting, switching to ac, resetting, shutting down. Nothing. The AC blows super cold, there's just no heat at all. I hear the compressor turn on when I turn the AC on, and hear it turn off when I turn the AC off.

I'm still not clear as to if this is a vacuum problem or an actuator problem. Does the vacuum control if it comes out of the upper vents, floor vents and defogger, or does it control the actuators? I can change the flow of air between all vents no problem.

Again, if it's an actuator problem, can I get part numbers for the left and right 2001 actuators?

madmatt9471

"Does the vacuum control if it comes out of the upper vents, floor vents and defogger, or does it control the actuators? I can change the flow of air between all vents no problem.

Again, if it's an actuator problem, can I get part numbers for the left and right 2001 actuators?"

Yeah you did try it all I wish it had worked like it does for me at times.

To answer your Q: Yes the vacuum does make the Vents adjust from floor to defroster. If it were broken then it will "NOT" cycle through these Modes!

As far as the Actuators - you do not need to buy new ones but you will need to re-index them as in the post here:
http://forums.corvetteforum.com/c5-t...actuators.html and here

http://forums.corvetteforum.com/1557915431-post68.html

I do not know the Part number for the actuators. There is also a fuse you can pull in the fuse box under the passenger floor board - it is in the thread here on how to re-index the actuautors - Read it and you will understand these crazy little parts

Thanks,Matt

stevenhmiller

Thanks Matt. I wish it worked also. I dread the thought of ripping out the dash, or doing anything in the dash. Well, I guess that'll be a weekend project one of these days. Thanks again!

av8rdavid

I almost tackled the project this weekend but the cold lazy weather kept me from it....I'm off Tuesday so i might just knock it out then.

I have to buy vacuum line and run a new piece from the manifold... uh!

Aerovette

Ok, I have read, read, and re-read the post and i am going to give this one more try before I give in to the expensive prfessionals. I have a few questions though.

1)What does the electrical connection do at the back of the IM and is it related to the vacuum or just a convenient location?

2)If the vacuum for the HVAC, the AIR and the brake booster all all shared, why do I need see any change in braking? If the AIR is affected and the HVAC is, it only seems logical that the brake booster has to be losing vacuum too.

3)How far can I flex the bottom of my fender before I risk damage to the panel or stress fractures in the paint that may not show up for months?

4) Which side of the check valve should allow or not allow vacuum? From what I can see, if I attach a vacuum pump to the point that the intake connects, I should be able to make the vent blow at the correct place by applying vacuum to the input point that the IM connects to. Right? That would tell me without a doubt, that it is the IM line that is bad. If the vents are unaffected by applied vacuum at that point, then it must be something under the dash. right?


All help is greatly appreciated.

P.S. GREAT write up !!!

salsvette

Matt,
Thanks for posting the instructions. I got as far as the vacuum control on the heater box and discovered that I had no vacuum from the supply line. However, I had no idea on how it was routed and GM is very stingy about revealing this information. I'll run a new supply line
next weekend

madmatt9471

I'll do my best to answer your questions:

1. The electrical connection at the back of the IM is the MAP Sensor - be careful to "NOT" snap it you can unplug it(Probably should) because the small vacuum line you need going to the heater controls is RIGHT Under It!!!!

2.NO! not necessarily, the Vacuum connection at the back is one piece but it has seperate ports in it, plus the Vacuum line going to you Booster is huge in comparison to the small line going to the HVAC controls - plainly it's just not enough to make that happen - it's almost like having a vacuum leak at the front of the IM and asking - why don't I see a difference in my braking? It's too small.

3. There is "NO" need to flex or pull on the access panel due to the fact that it is able to be removed and "IF" you ever have to pull on a panel for room then I would hope you will know how far to go - weather plays a factor in material - HOT= More plyable COLD= Less plyable

4. Simply put, to find the path one only has to see what direction it/Vacuum goes into the IM, the IM pulls the Vacuum to it, so if you were to pull the vacuum line off the IM and leave it connected at the Check Valve and blow air towards the Check Valve and it does "NOT" hold then you have a leak and you line if fractured and needs to be replaced-

The other way is to pull both ends( at the IM and the check Valve) cap one and either blow into it or put a vacuum sorce on it and see if it holds!

I hope this helps! my cell is 661-406-7516

Thanks,Matt