If you can hear the fan motor changing speeds i'd guess the resistor is good. It's got to be blowing out somewhere so check all vents for air movement (dash, floor and defrost). On my 87, I had to reattach the selector cable housing (the whole cable was moving when I moved the vent selector lever) but I did still feel the air coming out between the dash and floor vents. Maybe the squirrel cage fan fell off the motor if you're not getting any air movement. As for the heat, feel the heater hoses going into the firewall for the heater core, both should be warm/hot to the touch if the coolant is circulating properly. If there is a blockage one hose should be a lot cooler then the other.