I have a 2007 Chrysler Aspen, and recently (past 2 weeks) when I turn on the ac, I notice a 'foul' smell, like burnt rubber, or even sulphur-like. The smell will last a few minutes and will gradually fade away while the ac is running. Since this has not happened to me before, I need to know if something is going on with the ac. I would appreciate any help or suggestions with this concern.
You might want to consider the following answers. They might be relevant to your situation:
Here's a subset of what I suggested for the "heater" question:
Leaking gear lubrication (which can smell like sulfur) combined with a bad seal in the ventilation system (or an intake that catches a whiff). Check for drips under the car: they should have the same smell. If they're there, look for leaks around the transmission or differentials.
Hydrogen sulfide from the catalytic converter, again getting picked up by the ventilation system. If so, this is possibly a bad cat.
Hopefully, one or more of the above discussions will help you in this situation.
Try changing cabin Filter and see if that makes difference if you have not changed lately. Generally Cabin Filter is under Gloves Compartment on Passenger Side