Inspection of the A/C circuit will also reveal the high pressure switch in
the AC system. Since "Freon" pressure is also dependent upon temperature, if
the pressure exceeds a certain value (I can't remember what it is, 250
psi?), the fan kicks on high speed (HIGH speed). The fan will remain on even
if the van is turned off. My 87' did it yesterday for the first time this
summer (temps of 105 here), the fan turns off when the pressure in the
system drops below the switch point. This is to ensure the AC Still works if
it gets hot (HOT).

John
Aircooled.Net Inc.