While driving down the interstate if i turn my air conditioner past 2 (1-4) there starts to be a very loud hissing noise that sounds like it is coming from the rear driver's side part of the engine. If i then turn the A/C off the hissing goes away until i turn it on again. Any suggestions as to what is wrong with it? It is a 1997 Jeep Cherokee Sport with the inline 6.

 

Check all connections and lines. Do you have a factory service manual?

 

No i don't, i have a Chiltons book for it but that's it

 

All of the A/C system in on the right side of the vehicle, you sure it's not a vacuum leak under the dash?

 

IS IT "HSSSSSSSSSSS"? OR PSSSSSSSSSSSSS? HIGH PITCHED? OR LOW PITCHED? I MIGHT HAVE THIS ONE!

 

Haha now you've got me questioning myself.. I'd say it's more of a high pitch.. It starts out quiet and lower and then very quickly gets louder and higher. And i'm not sure about the vacuum leak under the dash. That very well could be it.

 

this link shows some of the vacuum operations of you ac mightg help locate the hisssssssssssssssss...http://www.jeep4x4center.com/jeep-se....swf#toolbar=0

 

Got it fixed! We pulled the dash apart and found that the door's that allow the air to go through when the mode is changed were just stuck. Thanks for all the help!