M103 1903 2.6 Hot coolant on right foot

[4uky]

I was driving today and got scalding hot coolant on my right foot in my 1991 190e 2.6.

In my Saab 900 era, I knew what this meant: the heater control valve was bad, and it was an easy fix.

I have been told previously the heater valve on this car is on the passenger side.

So what am I up against here? Is it the heater core?

Thanks for your help!