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1990 Cherokee AC vents/vacuum reserve question

Hi,

I have a 1990 Cherokee Laredo 4.0L 6cyl where the battery leaked and dissolved some vacuum lines running next to and beneath the battery. This causes the familiar problem of the dash vents not working with AC or heater. There apparently is a vacuum reserve bottle somewhere which may have been partially eaten by battery acid or otherwise have broken/dissolved vacuum lines going to it.

I have heard about this "reserve bottle" from a number of Jeep newsgroups, but nobody seems to know where it is or how to get at it. I have heard it is under the battery, or behind the bumper. I can see broken or dissolved vacuum lines going from under the battery into what appears to be something behind the bumper. The Chilton and Haynes Cherokee manuals do not describe this vacuum reserve reservoir bottle or show it's location.

Is there an easy way to get at the bottle to look at it, replace or repair it, without either pulling the radiator or taking the bumper off?

I appreciate the time taken to respond to this, the Jeep dealers here in CA are no help and the shops do not seem to have the ability to fix it properly.

Thanks in advance,

George

Reply to
George Underdahl
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Hi, George

On my Jeep Comanche the big black vacuum bottle is behind the front grill. Looks like a small football. You get to it from the front, removing 10 screws and pulling the front plastic grill off. It is easy to get to and has the vacuum lines just as you describe below the battery. I found mine installing a new radiator and having to unbolt the condensor from the front of the radiator.

Good luck, Craig

Reply to
Craig

Hi George, just heading out to remove mine. I refer to it as the vacuum blimp... I think Kevin in San Diego came up with that. So, on to business - it's located inside the bumper on the right side. I think there is 2 6mm bolts holding it. There doesn't seem to be any short cuts in removing it... I think the bumper has to come off. I'll post a follow up when I'm done if I come up with any tricks

-Brian

Reply to
Cherokee-LTD

Thanks for the input folks - everyone was pretty much correct.

I got under the Jeep and was able to pull off the road protection flap that attached with those knurled plastic spokes; that allowed me to get at the vacuum reserve bottle. It is on the right hand side, tucked into the bumper; it is like a small black football, and it does have two chambers. 3 of the 4 vacuum hoses were eaten through from battery acid, and the one plastic "T" used was cracked in half.

You can get at it from underneath this way; it is a devil moving around the thing though. You need to fit your hands into small places around sharp metal to pull off and replace the vacuum hoses. It would be easier to get at if you pulled the bumper or removed some of the small cross members, but faster to just work around it carefully.

I've got the replacement parts, now just waiting for the motor to cool a little and see if that fixes the vacuum issue.

Thanks again for the help and advice,

George

Reply to
George Underdahl

This is an easy fix. By 'the Jeep dealers her in CA are no help' do you mean they wouldn't do it for free? Does 'the shops do not seem to have the ability to fix it properly' mean they won't do it for free either?

Just curious.

Reply to
bllsht

No, the Jeep shops and dealers out here are generally top notch. I don't think anyone expects anything for free when you take you car for in service. In this case, it was "fixed" 3 times by shops or dealers over the past year, but simply never fixed properly or the time wasn't taken to dig down and get to the bottom of it, for whatever reason.

Underdahl"

Reply to
George Underdahl

The reason I asked was it sounded like you were knocking the dealers and shops. It's such a simple fix, it shouldn't have been a problem. If it's been worked on 3 times, and it's still not fixed, the knock is certainly deserved. :-)

There should be a check valve somewhere in the hose supplying vacuum to the 'football' or maybe built into it. It would be worth checking it for proper operation to avoid additional problems. It prevents the loss of vacuum to the A/C system when engine vacuum drops, such as when the engine is under a load. If it's installed backwards, you won't get air distribution where you want it, and if it leaks, the air will switch from the A/C vents to the defroster vents when you're under a load.

You should be able to blow through one side, but not the other. The side you can't blow through should allow nothing through. If it does, it needs replacing. The side you can't blow through goes to the engine.

Reply to
bllsht

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