Air conditioning on 2002Jeep Grand Cherokee does blow cold enough Added charge to low suction line but still blows the same also the same line seems to have moisture where the aluminum and rubber meet

My first thought was low coolant, but with the added point about the ac I'm leaning toward a blend door problem under the dash.

It sounds like your blend door isn’t operating correctly . The blend door simply is a flap that is designed to close off heater core when it’s calling for A/C , and opposite for heat . Check to see if it’s operating

This means you need to add more freon, you can take it in to get added or just go to your nearest auto shop and buy some with a connector and just turn your car on with your air conditioner on high, and connect the line to your can then to the low side of the air conditioner lines and hold the can up right so you let the gasses in, not liquid. when can is empty remove from low side and be careful disconnecting from can because freon is very nasty stuff and may still have a little in the can. and repeat until necessary.

A 1999 Cherokee with the compressor running can be overcharged or the compresser blown, ( not pumping) Most of the timw if this happens the pump is noisely when running with gauges hooked to the system and the compressor on the low side shold be low and the high side 175 lbs. or more. If it is and the lines coming from the compressor are hot on the highside(small)and coldonthelow ( bigger ) thenan air doormay not be working in the dash. a scanner may help looking thought the body control systems and find something not working correctly.

Check the coolant level, sounds like you may be slightly low....Be sure heater is on high when filling the system....Look for any air bleeds...

You may have created an over charged condition and at this point the a/c compressor will cut off on high head pressures. This can be verified by installing gauges to the systems high and low side service taps and reading the pressures.An overcharged system will start the compressor briefly but soon cuts off once pressure goes to 350 - 400 lbs on the high side. Acceptable pressures for this system should be no greater than 250 high and low suction should drop to 40-50 psi.You might recover the charge and evacuate the system,then try bringing the charge back to proper level.A sight glass in the reciever drier really helps determining proper fill.Once all bubbles have dissipated from the sight glass during charging ,one should stop at that point to avoid overfilling.Too much freon is worse than a low charge especially in hot ambient conditions....

Is the compressor engaging? If not he needs to find if a sensor issue if its fully charged or a low pressure or refrigerant condition. You can have pressure without refrigerant.

Low refrigerant charge or a sticking blender door. Check the suction line for temperature. A cold tube means that the charge is fine.

It's possible you are not getting enough coolant flow to your heater core. Try pulling the hoses off the core, blowing it out with air compressor, fill with water and blow out again. Try this about five times and see what happens. Alot of times these cores will plug up or have restricted flow. They will blow warm at low speed but it won't flow enough hot coolant through to stay hot on high blower speed.

Did you check your coolant level or was it low and you added to it at some point? If so the system my need to be bleed or worst case the thermostat is going bad.