a/c only blows cold air when driving. on 2003 Mercury Grand Marquis

My a/c blows when car is moving. the faster you go the more air comes out. pipes in engine are cold. but air only comes out when you are moving, as soon as you stop no more air. The fan speed setting has no effect on air flow. a/c works b/c air comes out cold just not coming in car unless you are moving.

Asked by for the 2003 Mercury Grand Marquis
If the car has a cabin air filter check that it is not restricted, also I wonder if the blower motor is at fault and as alternator output voltage rises a little when the engine is revved up maybe then the motor works a little more efficiently.
1 more answer
wow, i would have a shop check this for you. one of the vents may be open and it also sounds like your blower motor is not working.

get it checked at a shop.