Question about 1993 Jeep Grand Cherokee
The symptoms you describe (by now you've fixed this, no doubt) are a severe vacuum leak. if it were a lesser leak, you would get defrost part of the time when you are not pulling a lot of power, or in other words, driving down the road at a steady speed and not trying to pass or accellerate.
the vacuum lines in Jeep Grand Cherokee's are very 'brittle' and 'crack' and the rubber parts 'ionize' and fall apart, or 'leak' from that degradation of the rubber. if you are ingenious, you can disconnect portions of the system (focus on the last line coming off the intake manifold but also check all the lines coming off the intake manifold and even the valve cover breather, as any of these will cause a vacuum leak to occur and do exactly what you are seeing.
Jeep, of course, wants a relative fortune for these cheap rubber parts, but with a bit of ingenuity, you can cobb together the necessary fittings and reducers from other sources, like parts from WEST MARINE (a boat supply outfit) and make your transitions out of nylon, and or brass. Seal everything well with RTV, let it cure, and make sure each 'home made' fitting you build yourself is 'airtight' before you put it on the Jeep.
your vacuum diagram should be on the crossbar just above the radiator, on the right hand side of your jeep as you look into the engine compartment, for your reference. best if you do not take all of it apart, but work with one section at a time.
you'll find your vacuum leak, and then you'll probably have working cruise control and air vents!
Posted on Mar 14, 2009
It seems like a vacuum leak
Posted on Feb 21, 2009
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