Quote:
Originally Posted by brianhi
Hello I am having a similar problem to what you described in this thread but in my W123 300D. I am wondering if you ever came to a conclusion about why your heat smelled bad.  |
Yes I did come to a definitive conclusion, but I don't know if would also apply to a W123.
I've had this problem on three W124s now. Recirculation mode for the climate control is actuated by one of the vacuum pods inside the dashboard pushing a large plastic flap open and closed. This flap is located directly upstream from the heater core. It's padded with a thin foam material, I suppose for sound insulation as it opens and closes automatically. With age, the foam disintegrates and begins to travel the only direction it can--towards the heater core fins, where it sticks, melts, and produces the terrible acrid chemical smell that I described in the first post.
The fix is to disassemble the car until you can reach the front side of the heater core and remove the foam chunks--they come off with a stiff plastic brush, like a toilet brush, and a mild solvent like vinegar, without any damage to the heater core. On the 124, you get to the heater core by removing some trim around the bottom of the windshield, the windshield wiper mechanism, and the heater blower fan. Unfortunately I have no idea what the equivalent job would be on a 123 chassis car.