Ok I bought my truck last june. 92 f150. After awhile of driving with my AC on I noticed it would cut out and stop blowing thn come back. Eventually it quit blowin all together. Winter came around and I have heat but only from defrost..no matter what setting I have it on it will come out the defrost vent only. Not too worried about it as I have heat, but would like some answers. Blower motor? Vaccuum line? Anyone else run into this?
Thnks!

 

the most common cause of this is a little tiny white hard plastic vac. line under the hood, comes out of the heater box. they get brittle and fall apart.