A/C overcharge

Background info: My A/C quit. I have R134a A/C. I bought one of those do it yourself cans with a gauge. I follow all the instructions. Car running, A/C on max. I added the Freon until the gauge read blue. No cold air. The next day I tried again running the car, thinking maybe it needed to run a little while before it would kick in. Still no cold air. Then I checked the gauge again and it was 70 psi. Overcharge. What do I do now? Can anything fix this without putting in new A/C?

New info: I drove my car to and from work, then rechecked the A/C and now it's borderline overcharge. About 45 psi, maybe a tad over, it's hard to tell exactly with the gauge. It's on the border between blue and yellow if that helps. But the air coming out from the A/C is the same temp. as the vent air. Anyone know what is going on or what I should do? Should I keep trying to run my A/C, I'm guessing no. I don't want to permanently damage anything.

Sounds like you've got a bad expansion valve. If so you've have to evacuate the A/C system and install a new valve. If valve has failed, it won't let the freon enter your evaporator coil (under the dash) and, hence, no cooling.

Regards:
Oldengineer

I think that we need more information: Like, is the compressor kicking-in? Do you see bubbles in the receiver/drier sight glass? The system normally runs 250-300 psi on the high pressure side. What's with the 70 psi you're talking about? When you added freon (12 or 134), you did hold the can upside down to allow it to drain, right? Otherwise you'll only get gas into the system instead of fluid. You need fluid to make the system function. These may sound like stupid questions, but I don't know unless I ask.