I have a 92 Cadillac Fleetwood Brougham and the heater is only blowing on the floor and wont go to windshield nor the vents on the dash any suggestions.

Welcome to the forums!
Even though I don't have a factory manual, if I remember correctly the 92'* were vacuum actuated, except for the air mix was electronically controlled.
Hopefully one of our members is more familiar with this car & may be able to provide a schematic.
If you have a good dealer locally, they will often help with a free diagram/component list for your 92 Cadillac Fleetwood Brougham.
Possibly google and see if you can find a pdf service manual online, ya never know...