I have a nice Cherokee, but it has a few small problems. The first of which is a ventilation issue. The control panel does not control the system. It blows A/C air through the defroster no mater what setting I put it on. I assume it is a vacuum hose somewhere. Does anybody know where to look?

 

I am not sure what year you have but they are on the right side of the engine,you should be able to se the heater control valve there and the vacuum line that go through the firewall to the controller on your dash

 

There are two vacuum lines that penetrate the firewall. One is the vacuum to the selector. The other is the line to the valve on the heater hose. What you have is a classic no vacuum to the controls. When this happens, it goes to default, which is defrost. Is your reservoir hooked up? Got any whistles under the hood? Just trace it backwards