2002 DODGE RAM CLUB CAB Visibility Problems

I PURCHASED MY 2002 DODGE RAM CLUB CAB LAST SUMMER OUT OF OREGON THE PREVIOUS OWNER FAILED TO MENTION IT HAD THIS ISSUE WITH THE HEATING SYSTEM SO UNFORTUNATELY I DO NOT KNOW THE MILEAGE AT WHICH IT FAILED OR IF THEY HAD ATTEMPTED PREVIOUS REPAIRS. MY 2002 DODGE RAM 1500 QUAD CAB HEATING SYSTEM HAS FAILED. ONLY HEATS ON PASSENGER SIDE AND WILL FOG UP WINDOWS WHEN RUNNING HEATER. IF YOU PUT IT ON DEFROST TO CLEAR FOG IT ONLY BLOWS COLD AIR. ALSO ONLY OPERATES ON HIGHEST STEERING. WITH CHILDREN IN THE VEHICLE IT IS NECESSARY TO RUN THE HEATER DURING INCLEMENT WEATHER AND VISIBILITY IS GREATLY REDUCED DUE TO THE FOGGINESS OF THE WINDSHIELD CREATING A SAFETY HAZARD. AS THIS IS MY COMMUTING VEHICLE IT MUST BE DRIVEN DAILY. REPAIRS ARE ESTIMATED AT $1000 AND THE REPAIR MAN SAID IT WILL ONLY BE A TEMPORARY FIX BECAUSE...