Yes, there is a fuse for the temperature controls - but - it also controls a number of other functions that you would certainly notice as not working also.
I believe it is fuse #10
NOTE: be sure to read the "Related Question" below about this #10 fuse!
It may lead you to identify a problem that is the subject of a Ford recall of all Windstars.
It is much more likely the small temperature blend door motor/actuator has failed - a very common problem with Windstars.
The good news it the part is relatively "easy" to replace and not terribly expensive ($50).
See "Related Questions" below for more
The "Related Question" below is an extensive discussion on the 1999-2003 temperature control valve / heater control valve. It is likely the information will be similar to the 1997 / 1998 Windstar
electric window binds on 2003 ford windstar
There is no MAP sensor on a 1999 Windstar.
how to drain 1999 windstar
Generally speaking the seats from a 1999 Windstar will fit up to 2003 Windstars.
The CD changer is in the center console of a 1999 Ford Windstar
Not likely - the 1999 Windstar was a rather significant updating of design compared to 1995-1998 models.
how do you reset the anti-theft system on a 1999 Ford windstar
how do you reset the anti-theft system on a 1999 ford windstar
how do you reset the anti-theft system on a 1999 Ford windstar
Cómo puedo resetear el sistema telft de una 1999 Ford Windstar
Not very likely - the Windstar was significantly redesigned in 1999, and the dimensions of the vehicle were changed.