this is for my 2000 town car but why ask thier not too many readers .

Sitting at a lite , I get no cold blowing ..... when I start to drive It get very cold .

could this mean that I need to recharge the system?

Sounds to me like your AC fan is not working.

If your AC fan is not working, the refrigerant will not be able to get cold, will overheat, and the compressor will cut out when the temperature and pressure spikes, then it will come back on again as the airflow of motion cools the condenser.

How do I know this? had the same problem when I converted my Charger over to AC and did not install a seperate electric fan to turn on with the AC.

So check your AC fan before anything. On Town Cars, I believe this is inside of the fan shroud in front of the engine driven fan.

Your system might be undercharged.