I have an unusual smell coming from the a/c system in the car. Only happens after the car is hot and only noticeable when the car is standing still or moving very slow - a real problem in Philadelphia commuting traffic. The smell is almost a combination sweet / exhaust type of smell. I have had my mechanic check for exhaust leaks and he found none. Anyone had a similar experience - please help because it stinks and I dont want to trash the car over this problem because I had hoped to get at least 150,000 miles out of this car but cant stand the smell too much longer.

Thanks

Steve

98 Volvo S70 85,000 miles

I found this old post which describes the same problem

Aircon Smell[ALL/1998] posted by Peter Lim on
Friday, 26 September 1997, at 9:17 a.m.

I own a 1993 850 GLT 2.0 model. It's engine designation is B5204FS (20 Valves). A few months ago I'd replaced the evaporator unit. Since then there's strong offensive odour emitted from the aircon vents. The concentrated smell fills the car cabin in short bursts. When this happens I just flick off the aircon button (but leaving the fan blowing) and the smell disappears.

The problem is an elusive one though. The smell does not come on in any regular
fashion, ie everytime when the car starts. However, I observed that whenever I
accelerate the car from several start-stop situations (as in between several signalized traffic junctions) the smell starts to burst out from the aircon vents.

I've got the mechanic to check the air circulation flap and was found to be in working order, ie it responds to the air circulation button when flick on/off.
The under carriage of the car was checked too but no exhaust leakage was
found.

Several mechanics have tried unsuccessfully to solve this problem. Today, I drive sometimes without the aircon but the heat of the sun is almost unbearable for any long drives in the car.

I'm posting this message in the hope that someone may have an answer.
Many thanks.