1995 c220 Smell with heat on please help!
 

Hey Guys,

Trying to figure out how to approach this problem.
The car runs right etc...

When you turn the heat on, the car has a bit of a smell to it, it seems like coolant but I'm not 100% sure. The smell is faint but noticeable, to the point where my wife doesn't want to drive the car until it's fixed. There are no leaks in the interior or exterior. Which would point to something obvious.

Any ideas where to begin?

Thanks in advance,

George

A pinhole leak in the heat exchanger would usually show up as a smell before it got worse and started fogging the windows. The classic diagnostic would be to have the cooling system pressure tested with the heater on but the engine not running. I don't know if this is possible with your system, it wouldn't be with the ACCII in my 107. On my car I'd have to bypass the servo and plumb the system straight into the heat exchanger.

Hrrmm... Time to look into that. I really don't know that much about the hvac system in this car. Seems like a viable idea though. Can you explain further what you have to bypass in your car? or is there a way to isolate just the particular component involved and somehow test it?

Thanks in advance,

George

I agree with the above statement.
As well, everytime I engage the windshield washers, there is a kind of sweet smell coming into the interior ( M-B using " flavoured " washerfluid ) ?;
Do you have a cabinfilter & has it ever been changed?

Cabin filter has been changed about a year ago. Just took a look at it, it had a bit of debris, couple pine needles. Blew it off with some compressed air seems fine, and has no strange odor, which leads me to believe that the odor is being added upstream of the cabin filter.

I don't know if that helps or mean anything, but I guess it's easiest to rule the simple things out first.

Take care,

George

In that case, I'm afraid I have to agree with a suspect heatercore.

Get the heater core pressure tested. All that has to be done is to adapt a coolant pressure tester to the heater core inlet pipe on the firewall and plug the heater outlet. If you cannot do this you're self have the local shop do it. That should pinpoint the leak if it is the heater core as the only part you are pressure testing is the core. Good luck. John