AC/Heat....can only get airflow out of defroster vents.

I've searched for this problem to no avail...so here goes. 2000 Cherokee...I cannot make any adjustments to which vents the AC/heater blows from, I'm only getting air flow from the top defroster vent....I move the dial switch to dash vents and get nothing, the air still blows from the defrost vent. Same result for every other vent selection

I pulled the trim cover off and took out the control box only to discover that it appears to be electronically controlled from the switch to whatever moves the airflow baffles in the ductwork to direct the air. I've never seen this before, all the other vehicles I've ever owned used a push rod directly from the control switch to the baffle and was easy to figure out what was sticking. Any ideas what the problem could be or where to start looking?

From my understanding the AC/Heat vent system on all cherokees operate on vacuum. I would check your vac lines leading to the dash ( Passanger side inside hood - small vac line), and ake sure there are no cracks in them and your system is holding vac. Also you have a vac canister behind your bumper make sure its well and connected.

pete

Yep... If you lose vacuum, the door defaults to defrost. Check as jeepsrock says.

Bought a 96 XJ a few months ago, all the air came out the defrost vents. Ended up being the line from the vac canister under the bumper. Check the vaccum lines that run along the passenger fender. line got brittle and just cracked. 2 dollar fix.

You guys rock! That's exactly what it was. I found a hole in the line about a foot up from the canister behind the bumper. It was close to a rubber splice connector so I just snipped off about an inch of old line where the hole was and reconnected it. It's working great now.
Thanks. :yelclap: