Not to say what you did and what it fixed is untrue, but a disco'd vacuum hose fixing air flow and cruise control? The two are completely different and have totally different on/off procedures and mechanisms.
I'm going to have to tear into my FSM because that just doesn't make sense. Then...
I could write a long explanation or you could use WJJeeps.com - Jeep Grand Cherokee WJ 1999-2004
Trust me, it will become your bible. Join North American Grand Cherokee Association forum too.
Blend door issue I bet. VERY common in the 99-04 WJs. The pins will break (weak plastic) but there's many ways to fix it. YouTube and/or WJJeeps.com - Jeep Grand Cherokee WJ 1999-2004