I've checked the forum archives and can't find an exact match for my '92 240 symptoms. The temperature is always hot regardless of the slide switch position and whether the air is directed at the feet, defrost or through the I/P vents. I don't think its related, but last winter I had the thermostat replaced but it was cold then and didn't really notice the continuous hot air problem.

Should I try replacing the heater control valve which I understand is near the accelerator pedal behind the center console.

Thanks for any help.

I would try adjusting the heater control first- I bet it's just not going all the way to the closed position. Access through the left side cover of the center console.
A lot of these cars have more of an on-off heat control in moderate temperatures than an easily regulated variable arrangement (like you would expect). If there isn't any more adjustment left or it refuses to close, then I would replace the valve.
--
Rob Bareiss, New London CT ::: '86 244DL- 215K, 87 244DL- 230K, 88 744GLE- 198K, 91 244 180K