Air selector not working, replaced control module, no change. Blend door repair? on 1997 Jeep Grand Cherokee

Any sugestions?

2 answers 2 comments
please give more details on issues.ck for pwr to controller 1st
Air only blows on defrost, all other functiions OK: heat and A/C, fan speed, air flow.
Door door is either stuck or has inadequate suction for control to work. How do I check suction lines first before having to cut into door housing to check door?
97 Jeep Grand Cherokee Larado 8 cyl. 145K miles
likely...that is a common failure
Thanks