Diagnosis for a 94 mercedes c280


#1

I have a 94 mercedes c280 with 116000 miles on it, recently the passenger and driver air conditioning vents near the doors started shooting out hot air when air conditioner is on. The two vents in the middle still shoot off ice cold air… help?


#2

I don’t know the details on your car, but the hot coolant flow to the heater cores is controlled by an electric valve that looks like this:

http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.mercedesshop.com/&cookieid=1CQ0J3JZ42BL0VG1YH&year=1994&make=MB&model=C-280-001&category=R&part=ACC+Dual+Valve

On most of these cars, uncontrolled heat is caused by the valve failing in the open position for some reason (valve failure, loose connection, or failure of the climate control unit). Start by making sure the electrical connection on that valve is tight.