Vacuum Basics? - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ General Discussion Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 06-28-2011, 12:00 PM   #1
Newb
 
Join Date: Jun 2011
Posts: 5
Vacuum Basics?

Hello,

I have a '97 Wrangler. I have 4 wheel drive, but no cruise control, or really any other extra featurs. It is an automatic transmission 6 cylender. My heat / air conditioning will not rerout through the vents, and is stuck in the defrost position. After reading several posts, it sounds like I need to look under the hood for a vacuum leak. I have a few questions about the vacuum system.

1. Where should I look for the leak?
2. Which systems run off of the vacuum system?
3. What are some tell tale signs of a vacuum system problem?
4. How does the vacuum system work?

I'm fairly mechanically inclined, but I'm definitely no expert. I would really appreciate it if somebody could answer these questions for me as though they were teaching somebody who needed to be spoon fed. Also, any photographs would be very much appreciated.

Thank you! You guys are great!

BNicollCSU is offline   Quote Quick Reply
Old 06-28-2011, 12:19 PM   #2
Jeeper
 
freeskier's Avatar
 
Join Date: Mar 2011
Location: Longmont, CO
Posts: 2,515
The vacuum system on the Jeep is really simple and only controls vent position and cruise control. There is a vacuum hose that comes off the intake manifold, near the back. From their it travels along the firewall to the passenger side where you will find a T fitting. One way goes to the vacuum reservoir inside the fender and the other goes into the cab. From the cab it travels through the dash to the HVAC controls, then splits into all the separate hoses to control the different vacuum canisters that control vents.

I don't have cruise control, so I assume somewhere under the hood there is another T fitting or something to go to the cruise control.

Basically look for anything disconnected or any cracked hose.

BTW 4wd is not vacuum controlled, it's mechanical in the t-case.

freeskier is offline   Quote Quick Reply
Old 06-28-2011, 01:15 PM   #3
▄▌ee▐▀

WF Supporting Member
 
Hardermods's Avatar
 
Join Date: Jul 2009
Location: Kansas
Posts: 1,296
Start with this picture,



Number 5 and 2 on the lower right is where the connection on the intake is, the elbow of number 2 falls off the port ( 5 ) , reconnect there and put a ziptie around it. If its connected, follow the diagram until you find a broken or cracked hose.
Hardermods is offline   Quote Quick Reply
Old 06-28-2011, 05:13 PM   #4
Newb
 
Join Date: Jun 2011
Posts: 5
I think I found the problem. It looks like the end of the hose (#8 above) is not connected. It looks like it attaches to that box in the diagram above. Where is that box, and how do I get to it?
BNicollCSU is offline   Quote Quick Reply
Old 06-28-2011, 05:58 PM   #5
Newb
 
Join Date: Jun 2011
Posts: 5
I figured it out guys. Thanks a lot! I had to stand stand up on the front bumper and lean way over to feel for the nipple that that hose hooked up to. I got it on and it works! I think it's the first time in years that thing has pushed air out of the vents. Thanks again!
BNicollCSU is offline   Quote Quick Reply
Old 06-28-2011, 06:29 PM   #6
Jeeper
 
wirejock's Avatar
 
Join Date: May 2011
Posts: 175
Images: 11
Make sure the vacuum canister didn't rattle loose. That's what caused mine to come off. If you can reach it again, it should be mounted securely under the battery tray.
wirejock is offline   Quote Quick Reply
Old 06-28-2011, 06:59 PM   #7
▄▌ee▐▀

WF Supporting Member
 
Hardermods's Avatar
 
Join Date: Jul 2009
Location: Kansas
Posts: 1,296
Glad you got it, FYI it is easier to see that connection ( 8 ) if you lay under the right side of the vehicle and look up along the front of the firewall you can see if the box has come loose or if the hose you attached has any cracks that may cause it to come loose again.
Hardermods is offline   Quote Quick Reply
Old 10-07-2011, 03:48 AM   #8
Jeeper
 
Join Date: Oct 2011
Posts: 17
Quote:
Originally Posted by Hardermods View Post
Start with this picture,



Number 5 and 2 on the lower right is where the connection on the intake is, the elbow of number 2 falls off the port ( 5 ) , reconnect there and put a ziptie around it. If its connected, follow the diagram until you find a broken or cracked hose.
Quick question, what is line #4? I broke mine while changing my header and need to get it replaced. Thanks guys!

Molonlabemike is offline   Quote Quick Reply
Reply

Tags
air conditioner , defraust , heat , hvac , vacuum

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Vacuum shift motor inexpensive fix Coyote_94YJ YJ Tech Forum 117 Yesterday 04:34 PM
how to fix all vacume problems and how to locate the problems. Captaincoop1220 YJ Tech Forum 50 02-23-2013 12:19 PM
Carb Help!!! Burning gas! mogarber YJ Tech Forum 32 07-12-2011 01:44 PM
4WD to 2WD Integrated Vacuum Switch Jeepentg YJ General Discussion Forum 0 01-18-2011 05:07 PM



» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 07:12 AM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC