HVAC

The problem that I am having is that my A/C is not working! When I turn it on the air blows only through the defrost and the air compressor does not come on when I push the A/C button on the computer climate control and nor does it switch from vent in face or to vents on the floor. I bypassed the relay switch and the compressor came on I even bought a new computer climate control and the same thing is happening I tried re-calibrating the system and still nothing when I had bypassed the relay switch I was able to charge it up it blew cold air only from the vents in the roof of the truck rear air I guess the fan blows hard it is just only coming out through the defrost. Can anyone help? Thanks