I Messed Up My AC I Think

[BigJim1]

2003 Pathfinder LE, our AC would not start cooling until we had driven for about 7 or 8 minutes, then it cooled slowly and finally blew cool. Today I drove the truck until it was good and warmed up. The outside temps was 96 degrees F. When I hooked the gauges up without the engine running the
low side read 63 high side 175

engine running at idle AC Wide Open all windows up
low side 33 high side 255

engine at 1500 rpm
low side 27 high side 285

engine just shut off
Low side 64 high side 225

I figured it was a little low so I added a little R-134a and I mean just a little. I unhooked the can of R134a and opened both sides back up. The low pressure side pegged the needle. I figured I had over filled, so I relieved a little pressure. I noticed the high pressure side was dropping really fast and the low pressure side was not dropping as fast. I shut it all down and came in to ask what I did wrong and how to correct it.

The last reading with the engine off the low side reads 72 and high side reads 75.

I don't have a clue what to do now, any suggestions what my next move should be?

[Mike W.]

Disregard any readings with the engine off. At best they are meaningless and at worst will confuse you and be cause for bad decisions.

Your running readings look a little low to me, but I would still expect better performance. My '03 QX4 probably starts blowing cold in 30 seconds or a minute. Not stone cold as much as it will get, but you can feel the cool air. I'm guessing you were measuring either the pressure in the can when it pegged the gauge or charged with liquid. Hook up the gauges again, with it running and see what you have.

[Niti QX4]

What Mike W. said.