Air conditioning won't work unless driving?

I have a 2000 Ford Taurus. The air conditioning only works when I'm driving reasonably fast. I thought it was the blower motor, so I changed that but the air still does not work right.

Any suggestions?

Either install a ac Fan in the aluminium grill of the ac which face the front of your car or try pouring coolant in radiator. Also check the gas of the AC most of the times it leakes slowly and this probelm occurred

Geez, I thot for sure it was blower fan not working. Had that happen on 2 transit buses I drive, and sure made difference when new blower was placed.
Because, even with no fan blowing, the air being pushed in while you drive, will work itself thru the heater/a/c pipes and come out into the car, just at a tiny amt.
So something is making the a/c not work, unless drivng fast.
When driving fast, the air is moving fast around car, and the motor is causing fluids and pumps to work harder. So perhaps the a/c condensor is bad? Maybe you need to have a/c fluid recharged? It does wear out. Those are easiest things to check out, if it wasn't the blower motor.