need help with ac controls

[chickenlegs]

i just got a 89 cherokee larado 4.0 4wdrive. ac or heat stays on defrost. cant find vacum leak. any other places to look? also would like to use as tow vehicle for rv trailer but scwats when hooked up. have new moroe load levelers in rear. class 3 hich. reciever is 8 " from ground when hooked up. wondering if extra leaves in rear springs would help. not towing very far ( 50-60 mi. )

 

[ehall]

You have a vacuum leak, just got to find it. The outlets are controlled by vacuum lines that meet at the back of the control unit, and you might be leaking there or you might have low vacuum on the engine harness that is getting picked up by the HVAC controls. If you can afford it, you can buy a basic vacuum tester at the parts stores for $25 give or take (behind the counter at autozone).