why does hot air blow on the driver when COLD air is blowing everywhere else in

I think the problem is caused by your A/C's Drivers Side Temperature Actuator. Have it checked.

WE HAVE A 1998 BUICK PARK AVE,3800 SERIES,V6,BASE MODEL & WE HAVE HAD THE DOOR ACTUATOR ON THE DRIVERS SIDE REPLACED.AND EVERY TIME THEY CHARGE OUR AC SYSTEM THE AIR BLOWS SUPER COLD OUT OF ALL VENTS,FRONT & BACK.THEN AFTER AWHILE GOES BY IT STARTS OUT LESS COOL ON THE DRIVERS SIDE AND THEN TO WARM AND THEN THE SAME ON THE PASSENGER SIDE.THIS CONTINUES TO HAPPEN EVERY TIME WE HAVE IT CHARGED.IT SURE SOUNDS LIKE THERE IS A LEAK BUT THEY CAN'T SEEM TO DETERMINE THAT AND WE JUST KEEP HAVING TO PUT OUT MONEY & THE PROBLEM IS NEVER FIXED.I HAVE TO BELIEVE THAT SOMEONE IN THE AUTO REPAIR INDUSTRY HAS COME ACROSS THIS PROBLEM & KNOWS HOW TO FIX IT.I BELIEVE THERE ARE AOT OF SMART MECH & AUTO AIR PEOPLE WHO DO KNOW THE ANSWER.NEED HELP CAN'T PUT ANY MORE MONEY OUT AS ON A FIXED INCOME.