W114 chassis have left and right hand heater cores and controls for heat.

If the left side isn't defrosting, it may also be because of a no heat condition on the left side.

Heat is regulated by a valve on the firewall, controlled by a bowdin cable.

Jim

__________________
14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles