I'm trying to recharge my A/C system with a hose/gauge manifold (the red, yellow, blue hoses) after pumping out all the pressure in the system. The problem I have is when I attach a can of freon on to the 134a can-tap and turn the handle that will screw the needle down to push down the piston that will let out the contents, nothing comes out. I don't hear gas escaping the can, nothing comes out when I try to release pressure from the yellow hose, nor was there any gain in pressure on the blue gauge when I tried releasing it into the system.
Later I got a can of freon that I haven't tried yet, attached them to a single gauge and hose, saw that the can worked; and then when trying the can-tap from the hose/gauge manifold (and having it fail again), it would not work with the single gauge/hose afterwards.
Another thing I should mention is that the hoses, gauges, can-tap, cans of freon, and vehicle's A/C system are all 134a.
So what's going on? It looks like I'm breaking the can's piston every time yet I'm taking it slow and being very careful. Do I have a bad can tap? Or am I doing this wrong?