My ac does not work properly when I add freon the ac will work well for about 5 minuted then will blow warm air hoping some one could give me an idea what might be wrong, ie what to replace to fix it.

Sounds like you have a leak in your coolant system somewhere.

To give you a better answer, a little more information would be helpful. What kinds of time frames are we talking here? Are you adding freon, immediately turning the truck on with the A/C on full blast and its only lasting 5 minutes and then returning to warm air? Or are you adding freon and then waiting several hours before driving with the A/C on?

The amount of time between when you put the freon in and when the car is started with the A/C on can give you a better idea. If you put the freon in and wait several hours before running the A/C or driving the vehicle and you don't even get the 5 minutes of cold air, its more than likely a leak in the coolant line. If you still only get 5 minutes of cold air even after letting the vehicle sit for a few hours with new freon in it, then its probably not a leak, but a whole different issue.

Does the compressor keep cycling on and off ? if so then it is low on refrigerant causing the cycling, sometimes you have to bypass the compressor pressure switch to stop it from cycling long enough to get enough refrigerant in the system, but of course you need to check for a leak if you are trying to recharge the unit then add a refrigerant with dye solution in it to locate any leaks, note leaks and then evacuate system amd rapair the leak source and then draw the system down add the proper compressor oil or refreigerant with oil in it. you may want to have a qualified AC repair facility do this , so they can properly evacuate and recover the refrigerant material... thanks , please rate my help...