Guys, maybe we have Late 1994 delanair system pro's here.
Upper part of blower seems not be operative as it should - nor internal blower regulator motor is working (Although itself it's working separately) nor upper blower flap is opening and closing correctly (physically/mechanically works fine).
It seems like the system is not controlling upper part at all.

Blending on footwell part works absolutely perfect - cold or hot if required comes as requested.





Any help?

 

That flap will only open when air conditioning is called for. For heat or defrost it stays closed. It also takes a while to stabilize, it can be up to a minute for that flap to open once the AC starts blowing cold.

 

I second what Jagboi64 says, also check the flap is not physically stuck in place. The foam sealing strip quite often breaks down into a gooey sticky mess and holds it closed.

 

dear @Jagboi64 and @baxtor - air circulation went is always in COLD position (open only for cold air). I've checked the motor separately - it's working. But it's not working while connected in the car.
All foam is cleaned.
Center air went is not opening as well.
Seems more like electric problem...
Although as mentioned - bottom air circulation (Footwell) is working absolutely fine.

 

Have you checked the vacuum system and solenoids.

 

Solenoids - physically working fine. Each (there are 2) working separately one from another and opening physically valves. Though - center went is not opening automatically from vacuum. Demist - works from button perfectly.
Vacuum lines are keeping vacuum and seems to be intact.

 

You may have these resources already but in case not, here they are.

 

Dear @baxtor thank you for the information provided.
Previously i've fully rebuild this box - new AC condenser + new heater matrix. Maybe during assembly i've wrongly installed the upper flap and thus it's working incorrectly.