Scotty… I bought a used 2006 Jeep Grand Cherokee Laredo. 3.7L v6. Got around 150k on it. Decent SUV. However. When I test drove it, everything worked great. A couple days later the AC blew warm. I added a full cab of R134a to it(24oz) and it blew great for about 5 days. Then ..warm air. I tried to recharge it again but it only Lasted a day or so. I’m not an AC guru or anything.. any tips????
You have a leak. Use UV dye or an electronic detector to find it. However if you are not familiar with working on air conditioning it might be best to take it to good independent shop.
Never use those cans of refrigerant from the auto parts stores. They will ruin your entire system. As Chuck said, you need to take your car to an AC professional.
Those things should be outlawed. They're selling the fraud that by hooking up this "magic" canister and "filling to the green" you'll magically repair your air conditioning. I've even seen some now that have a fancy-looking electronic low side gauge to give the impression that ooh, it's really diagnosing things now. Then of course many if not most contain potentially damaging sealer that can plug up your AC system and you have a real crapulent product. (Of course fraudulent "magic" car products have been around since almost the dawn of the automobile age. I doubt they're going away any time soon.)
The shame of it is that you can get a decent manifold gauge set at low cost or maybe even borrow one from a parts store for free, and pure R134a is pretty cheap at places like WalMart or Tractor Supply. Not difficult to do either, plenty of videos out there show how to use the gauges for basic diagnosis and charging.