2003 Durango a/c problems

My a/c is not cooling very well. A friend put two cans of 134a in and now it is blowing vapor from the back side of the compressor. Compessor also shuts off and on about every 3-5 seconds. Did this before the first can of 134a. Any ideas before I take it to a shop?

A/C was overcharge after the 2nd can and the low pressure side valve was leaking. A/C will almost make ice out of a cup of water.

How do you know that the system is overcharged if you are using the little cans? Do you have a guage also installed? What are the readings ( both high and low side)?

Had to take it to the shop to find that out!

I posted a thread a couple years ago about the A/C on my '98. Sounds like the '98 was a typical experimental piece of work, with many gremlins. I tried the re-charging route, and did the same thing, over-charged it. Took it in for diagnosis, and one of the 10 possibilities quoted by the repair shop was the little *#!@ flap things that seal off the heater core from the A/C coil. Apparently they do not seal, so during summer, you get as much heat out of the A/C as you do cooling. I followed someones advice, and do a semi-annual ritual disconnecting the heater during summer/re-connecting in fall. Works fine like that.