The blower motor does not heat the air, per se. Air movement is what it uses to clear the “fog” away, using cabin air.
The heated glass design uses electric heating grids on glass to do the same thing (remove fog) - but also removes “frost”, snow and ice, as well.
I have had cars with both designs. The blower design is great to retrofit to a car without either system.
If you currently have a defroster system (glass grid), it might be best to find out what is wrong with and fix it.
DCAspen,
Do you have a faceplate with defroster and rear wipers?
BudW