Hi, my name is Bob
I just bought a 2001 Cherokee and the A/C works, just on the top of the dash(defrost) but not out of the front vents. I also noticed no cruise control.
I am told its a vacuum issue with a broken line or something
I am a newbie, sorry if this has been already covered

 

You were told correctly.

 

To elaborate further, check behind the passenger side bumper and make sure the vacuum ball is hooked up and the lines are the cruise control system and snug together

 

Not only that, but there are some hard plastic lines that run along the right inner fender area to the cowl/firewall.

These are prone to harden with age and heat, and crack. Or a hole can be abraded in one.

It doesn't take a very big hole or crack to kill the vacuum signal to the cruise and blend door.

 

Yup, check the vacuum ball and the inside passenger side for broken vac lines. I fixed my friends with electrical tape and I don't think he has bothered with it since.

 

Somebody needs to do a write-up on this as it gets asked very frequently. Firestorm?

 

Here's a pic that shows the HVAC vacuum tube routing and the vacuum reservoir, if it will help.



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I dealt with this exact same issue. It turned out that my vacuum line going from the vacuum reservoir to the cruise control servo was rubbing on my battery mount and had worn a hole in the line. About $1.20 worth of vacuum line later, problem solved...

 

This diagram doesn't help me too much. I have an 88 and ive checked the lines and bottle in the engine compartment but no fix. I'd there anything with more details including the in cab diagram?

 

The problem is not likely in the cab. Do you have a vacuum pump for bleeding brakes? If so, follow the vacuum line to where is connects to the intake manifold. Pull the vacuum line from there and hook it up to the vacuum pump and try pumping it up. If it builds vacuum pressure and holds it relatively steady (you will likely have a little pressure loss) your problem is not likely a vacuum issue. If you cannot pump it up and get pressure, you have a vacuum leak somewhere and that is likely your culprit.

 

There is a vacuum line coming off the back of the manifold, plugs into a check valve, then runs into your cab. Check this valve. Air should only travel one way in the valve of course.

CCKen I used your pic for claification.

 

Does anyone have pics of under the hood to make it a little easier. Im starting from scratch and dont know which vacuum lines I actually need

 

You need all of them if you want every vacuum actuated system to work. Lol. CCKEN posted a pic of the vacuum system under the hood. Scroll up.

 

Here

 

Here's a couple photos of the vacuum system in the engine bay.

I used a Harbor Freight brake bleeder vacuum pump to run the system down to around 17 in. Hg., with the Heat/AC mode slector Off (O). The fitting I connected to is normally attached to the intake manifold. I used a 1/4" X 1/4" barb coupling to connect.



This view shows the vacuum line at the juncture where it tee's off and goes into the firewall. After entering the firewall, the tube goes to the Heat/AC mode selector as the main source of vacuum to operate the HVAC Unit valves.



After the tee in the above pic, the tube goes to another tee behind the cruise control servo. As can be seen - sort of :-), the tee-off is the source of vacuum to the cruise control servo.



After leaving this tee, the tube goes behind the battery and through a hole in the grill support structure to the vacuum reservoir. I wraped the tube behind the battery with 1/4" corrugated split loom to help protect it.

A quick look at the reservoir can be achieved by rolling back the front edge of the right wheel well liner below the right front bumper end cap. A flash light and a mirror may assit in getting a good view of the reservoir vacuum tube attach point.