Help with A/C mode

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Apr 18, 2009 | 10:28 PM

Cj5marietta

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7th Gear

Joined: Apr 2009

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Help with A/C mode

Has anyone ever had their air condition mode stuck in Bi Level position? No matter what position I try to move to it stays in Bi Level. Thoughts?

Apr 19, 2009 | 06:34 AM

Bill Curlee

Tech Contributor

Joined: Dec 1999

Posts: 32,910

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From: Anthony TX

CI 6,7,8,9,11 Vet

St. Jude Donor '08

The HVAC damper doors all work on VACUUM. Your missing the vacuum signal to the HVAC unit. The vac signal comes from the back of the intake manifold:

The vacuum hose is that little tiny nylon hose with the 90 deg rubber fitting on it. If that line is off that fitting, damaged by battery acid (it runs inside the wiring harness that runs under the battery)
it will loose all vacuum and the HVAC unit will not function properly.

BC

Apr 19, 2009 | 12:38 PM

Cj5marietta

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7th Gear

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BC thanks for the pictures and information. Can you get to the hose without removing the intact manifold ?

Apr 19, 2009 | 01:33 PM

Bill Curlee

Tech Contributor

Joined: Dec 1999

Posts: 32,910

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From: Anthony TX

CI 6,7,8,9,11 Vet

St. Jude Donor '08

I have in the past reattached that hose to the nipple when it fell off. BUT,,,,,,,it took a lot of blood sweat and cussing. You will need a mirror and a flashlight to see anything back there. Use the mirror to examine that fitting and just make sure that it attached. 9 times out of 10, the nylon tubing is damaged somewhere in that wiring harness or the vacuum resivour in the passengers fender well is damaged.

Apr 19, 2009 | 01:41 PM

nickk4469

Instructor

Joined: Jul 2005

Posts: 229

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From: Burlington michigan

Yep

I got lucky and just had to reset mine, its been awhile so i really dont remember what fuse i had to pull to do it. mine was stuck on heat only on the drivers side but the air conditioner worked great on the passenger side. I'm sure someone can help you out.

Apr 19, 2009 | 02:19 PM

Bill Curlee

Tech Contributor

Joined: Dec 1999

Posts: 32,910

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From: Anthony TX

CI 6,7,8,9,11 Vet

St. Jude Donor '08

Quote:

Originally Posted by nickk4469

The HEAT AND AC temp are controlled by electricly controlled servos. The doors that control where the air (what ever temp you make it) are controlled by vacuum controled servos.

Here are the vacuum servos:

Here are the electronic controlled servos:

Here are the electric and vacuum servos side by side.

Apr 19, 2009 | 02:34 PM

Bill Curlee

Tech Contributor

Joined: Dec 1999

Posts: 32,910

Likes: 2,402

From: Anthony TX

CI 6,7,8,9,11 Vet

St. Jude Donor '08

Check out this link

http://forums.corvetteforum.com/c5-t...with-pics.html

Apr 21, 2009 | 05:50 PM

Cj5marietta

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7th Gear

Joined: Apr 2009

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Thanks, man now all i need is a mirror to check behind the maniforld. I did just discover some oil or maybe antifreeze over at the fender where the wires go behind and under the battery, i think the two hoses from the motor might be leaking antifreeze ! The hoses are original 8 years old so maybe it is time i replace the hoses. Do you think that might have an effect on the vacum ?