Bill,

The same problem just happened to my 86 Syncro.

Check to see if you have some water collecting in the housing under the
evaporator.  This can happen if your drain hoses are plugged and/or the
housing is sagging because of the infamous cracking of the support
brackets.  The excess water can be in contact with the bottom of the
evaporator, leading to poor air circulation and icing up of the system.
That would create a lack of cooling and moisture being blown through the
ducts.

Also check to be sure that your a/c thermostat capillary tube is properly
positioned in the evaporator housing and that your front cooling fan is
working on all three speeds.

Good luck.

Budd Premack
86 Syncro, 73 Super
Minneapolis, MN (Land of Sky-Blue Waters)