Help me decipher the blend controls please! 92 Limited

[NaturalMystic92]

Hello everyone,
I'm a new member, this is my first Roadmaster! (92 Limited Sedan) I acquired it from my girlfriend's brother, who blew the transmission. I put a built-up one in and all is well! So now, going through and getting it ready for the road again, I cannot figure out how to run/what buttons to press for the blend door controls on this head unit (Hopefully image attached). Is there some combination of buttons that have to be pressed to make the air come from the defrost, face, and feet? Or is it fully automatic and will adjust it itself? Being it has been winter in northern MN for me, I've just had the temp set at 90 (if lower temps, does it change on its own??) and it stays at my feet when Econ mode is pressed. Defrost button makes it go there, but I can't figure out any other way.
Thanks in advance! RJ
P.S. Please tell me there is some complicated way of doing this, three of my car-guy friends and I sat down for an hour and couldn't get it haha.

 

[HotZ28]

If the system is working as designed, the owners manual Part #3 may help you. IIRC '92 & '93 were the same system. http://www.vadengmpp.com/owners-manual/buick/1993-Buick-RoadMaster.pdf

 

[NaturalMystic92]

Ooh I was missing the manual; thank you for the link! The manual says there should be a "mode" button where mine displays "ext temp", so...I guess I'm not sure, maybe it was swapped in at a later time, I may just look for another factory one and swap it back if it doesn't work in the next few weeks. It's still snowing here so the Subaru stays out haha. Thanks for the answer!

 

[Griswold]

Is it automatic? There is a button to select defrost, but otherwise does it select floor heat or AC depending on the temperature?

 

[NaturalMystic92]

It is automatic, but it always selects foot. I guess I can try to pull it into a shop and see if it does depend on temp! We haven't really had it up to operating temp with a warm day yet, and I haven't tried to let it blow cold air on "Auto" for too long yet, will it just do it automatically?

 

[Griswold]

Mine isn't a 92, but if you lower the temperature setting to the lowest it will switch to AC (or vent if it is too cold already). Yes, it should switch between AC and heat by itself if the temp is changing inside the car.

 

[NaturalMystic92]

Update: All is working! It's nice-ish (40 degrees F) here and the auto function cycles it around. Thanks!