AC light blinking

so the weather's been pretty hot, and my ac light has been blinking for awhile. I never really thought of diagnosing my ac issues until the weather got really hot recently. Here are the thing's I've checked.

1. Fuses are ok
2. Freon is fully charged
3. relay... Tried the matching one from the fuse box and I get the same condition. When I jump a wire, the compressor comes on, and it blows cold air. Also the ac light remains solid.
4. jumped the pressure switch as per the FSM and no change.

Any other ideas? I'm assuming based on the above that the compressor is still ok since it works when I jump the relay. I read about the rpm sensor on the compressor but how do I check that?