it was fixed! it turns out that the AC IS o.k. but the heater was on .a simple solution was made ; the hot coolant hose that feeds the dashboard was disconnected and pluged with a sparking plug!! this means in winter I may not be able to defrost the windsheild. but herein the middle of arabian desert we rarely have cold days in winter

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Omar
UAE
1997 silver , Avantgarde
E320 W210
101000 km