Hot air only comes through vents when below 80°f

caddydylan02

Not sure why, but I can only get air through the vents in my 1990 deville when I set the temp below 80°f. Anyone know why this is?

PF_Flyer

I recall those posts... I think

imidazol97

I'm operating on faint recalls of posts in Buick forums.
It seems to me that some early 90s Buicks had the same
configuration to their dash vents so that they couldn't
be used in colder weather to warm hands as soon as
there's warmth in the air like I do. There was something
in the logic assuming if you wanted heat it needed to
come out at floor level (or defroster and floor)
rather than dash. It seems to me the automatic systems
on Buick leSabres changed that in 1995 to the system
used through 1999 leSabres.

After that the whole HVAC box changed to a different
system.