Buick 1993 Roadmaster Owner's Manual page 129

If
your Buick has the Electronic Climate control option,
it looks like this:
The following information tells you how it works:
Mode
When you press the MODE
button, it allows you to
select the outlets you want
heated or air conditioned air
to come
fiom.
Ybu can
select from UPPE,R,
LOVWR or BI-LEVEL
outlets by cycling ihrough.
the MODE fdnction.
The blower and the temperature will continue to be in an
"automatic" MODE unless you change the TEMP or
FAN controls.
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