My heat does not blow hot? Why on 1995 Mercedes-Benz S500

The blower blows cold air; It blows well; but it will not blow hot. I push defrost; its cold, recycle air button, still cold?

Asked by for the 1995 Mercedes-Benz S500
poss thermostat stuck open or vent door issues
1 more answer
Check your coolant level too!