if you could see it streaming out of the vents id say you lost the evaporator core as freon was leaking up through the vents. its in the box with the heatercore. theres a vent that goes from the heater core to evaporator core when moving from hot to cold.then the fan blows through it. also as stated not enough freon due to the leak means no compressor will com on. good luck, we dont have too much longer then it will be air conditioned out side.