if you removed the evaporator (inside the car or thru the firewall), you probably did something which allows air to flow thru the heater coil. the a/c can overcome the heater if the water flow is cut off, but hot air will come in at first. with the engine running, turn the input air control to outside air, then to max air or recirculate. you should hear the vanes moving. if the vanes are controlled via cable there should be resistance both ways. most cars have a self protect mechanism to prevent the compressor from running if the refregerant charge gets too low.
