My 2000 Maxima SE has the optional "auto temp control with digital outside
temp display."

Recently, when it is 50-60 degrees outside, we can't feel comfortable by
setting the temperature dial to 74 degrees. Cold air comes out of the vents
(whether dash or floor).  With settings from 74 all  the way up to 84
degrees it just pumps cold air. And it seems like the ac is running.

But when set to 85 degrees, which is the maximum setting, the heater kicks
in full blast.  Tried the ECON setting; still won't warm until set to 85
degrees.  It's gets stuffy very quickly in the car with the system turned
off.

What I am expecting is gradually warmer air as the temperature setting is
increased. I'm quite sure it worked that way until just recently.

I took it to a Nissan dealer in Omaha.  They checked everything out and
can't find the problem.  Any suggestions I can take to the dealer or try
myself would be appreciated.

Thanks.