The A/C system on my '00 S40 is acting up. After it is used for a time, the flowrate drops dramatically, almost like the system freezes up (but I know it doesn't). For a period of time, only warm ar is dispensed at a very low flowrate. After the car sits for a while, the A/C is frigid cold again. I had Vovlo do a freon pressure check - a-o-k. They even replaced the general vent fan but the problem lingers.

 

Keep an eye on your recirc buttom and light. They are programmed from the factory to change over after a certain time to fresh air.

Maybe that is what it is doing.