No Cold Air Entering Car
 

I HAVE A 1977 300 DIESEL. THE A/C COMPRESSOR AND FAN WORK FINE BUT THE COLD AIR DOES NOT COME OUT AT ANY SETTING, ONLY WARM TO HOT AIR. THE DEFROSTER WILL BLOW YOU OUT OF THE CAR. PLENTY OF VACUUM. IT SEEMS AS THOUGH A GATE IS STUCK UNDER THE DASH TO LET THE COLD AIR CIRCULATE INTO THE CAR. ALSO, WHY WOULD THE HOT WATER CONTINUE TO CIRCULATE INTO THE CAR? THANK YOU FOR ANY HELP AS SUMMER APPROACHES IN MIAMI. BLUEFOOT.