There seems to be 2 issues at work here, your lack of A/C compressor engagement, and the air coming through the defroster vents.
How did you check the Freon? Does the car still have R12, or has it been retrofitted?
The air going through the defroster is consistent with no vacuum getting to the HVAC system, because the air diverters are all vacuum control, and will default to defrost with no vacuum. The temperature blend door is electronic. Start by confirming the vacuum line going to the firewall is intact and properly connected. There is more to the system beyond this, but this is usually the most common problem area with a car this age.