Your blower motor is controlled by a master switch that is vacuum actuated.
The blower will not come on in any setting besides defrost unless you have at least 15 to 20 hg of vacuum.

Look for a leaking vacuum acuator, or bad fitting or valve somewhere in the system. The ACC2 system is a carbon copy of the climate control system used on 1970's Chrysler Imperials and was never really engineered for the 107.

If you don't believe me, check out the Chrylser Imperial club website http://www.imperialclub.com/Repair/Lit/Master/281/index.htm.

Now you know why the system is such a piece of sh%%#%#@%

Ed