I have the same hot air coming out of the side vents and windshield vent, but only while sitting in traffic or climbing a long steep hill. Otherwise the AC works fine, and the fans come on when they should. Is this the monovalve http://catalog.peachparts.com/ShopByVehicle.epc?q=1993-Mercedes--Benz-190e--.6-Climate--Control&yearid=1993%40%401993&makeid=63%40%40MERCEDES+BENZ%40%40X&modelid=6132%3AMBC%7C1486%3AED%7C10000011%3ASM%7C847%40%40190E+2%2E6&catid=242213%40%40Climate+Control&subcatid=242325@@Heater+Valve&mode=PA

if so, where is it located and how hard is it to change out? thanks

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)