97 Volkswagen Jetta A/C broken

The air conditioner in my 97 VW Jetta GT decided to stop blowing cold air. It had been working just fine two days ago. Today, when I turned on the a/c, it sounded like it kicked on, the air got a few degrees colder for just a moment and then return to outside temperature. If I allow the car to sit for a few minutes and then start it up it will give me another moment of coolness but will return to outside temperature. Here are the things that I have tried/checked. I tried adding coolant but the system would not accept any more. I checked to see if the compressor remained engaged once I activated the a/c and it did. The blower motor works fine on all speeds and the radiator fans function normally. Any Ideas?

Feel the lines going to the evaporator. Are they getting cold? If they are, the problem is the blend door, which controls air temperature inside the car by directing incoming air through the heater core or the AC evaporator, or a “blend” of the two.

If the lines are not getting cold, you need the help of an automotive AC specialist. You can play with those parts store refrigerant cans, but only an expert has the correct equipment for proper servicing of the AC.

Besides, sometime those cans explode, and that would ruin your whole day.

Thank you for the quick response. I tried running the ac for a few minutes while feeling the lines. Sadly , both lines were quite warm with the smaller one being almost too hot to keep hold of. Any suggestions on were I can get it checked out fairly cheap?