The Freon probably needs to be recharged. Any repair shop should be able to do this. They should also test the system for leaks to see why the Freon leaked out to begin with.
Vacuum hose that runs over the thermostat housing is leaking at that location.
your blower motor is stuck on low
A vehicle air conditioner has two basic components; the compressor, and the fan, or blower. If the compressor is working, the air coming out of the vents will be cold, but if the blower is not working, the air will not come out very fast. Hot wire the blower to the battery, to bypass any fuses or switches, and see if the blower will run. If it does, but will not run when connected normally, check the fuse for the blower. If it is good, you would be wise to take the vehicle to an automotive electrical specialist to have them troubleshoot it.
Need to know if the blower is working or not or, the air coming out is cold or warm or hot or, the air (hot or cold) is only coming out the defroster.
Need more info like, is the blower working or not, is the air coming out cold or warm when it should be hot, is the air not coming out where it should be.
The air should be comming out of the defroster vents. If so, most likely, it is the vacuum line that controls the vents. It is on top of the engine below the air cleaner, and runs to the front right of the engine. Buy the replacment so you know what your are looking for.
You're blower fan isn't working at all, but when you're driving air will still come in through the vents. Obviously, the faster you go the more air will come in. If you're just parked, no air will come in. Check you're fuse, blower motor, relay, switch, and resistor. It could be any of those. Sorry I can't be anymore specific. I'm just basing this on what you described.
If you have no air coming out of the vents then you need a new blower. If you have air but no heat its either the hot cold selector not moving the flap or its the heater matrix. First things first. Check the fuse for the blower (if you get no air). Everything except the fuse need a mechanic or very keen DIY expert with a Haynes manual to hand.
Check blower motor fuse Blower motor resistor pack? Fan switch? Selector switch? ---- Is the Blower Motor Working? I'm not sure if the question is that the blower motor is working and "no air is blowing thru the vents'! If the blower is working and no air is blowing thru the vents then you could have a broken Recirculation Door. That is another common heating problem with the 99/04 Jeep GC. The recirc door brakes and falls down blocking the blower which will reduce or block the air flow completely. Normally the dashboard would have to be removed to replace the broken recirculation door. See the Link below for a NO Dash Removalrecirculation door fix. ----
In the duct work of the air system you will find what are called "blend doors" Sometimes these doors begin to stick. Some are electrical and some are cable controlled. In most cases they cannot be repaired. They are easy to replace if you have easy access to the area behind the dashboard
Need to know if the blower is working or not and if the air coming out is hot, warm or cold.
It's somewhat cold. It's just very little cold air coming out. Can't hear the vent blow the air as well.