Internal Cabin Air Filter?
 

First thing we did our first FEH was install an activated carbon cabin air filter. My wife has MCS and could not chance contaminated outside air getting in. We also use a carbon air filter plugged into the AC socket inside the car. Very convenient that it is turned on/off with the key BTW.

Now I am looking for a way to filter the recirculating AC/Heater system. Anyone know if there is a place for one, or where should I look for the air inlet for the recirculating system?

RayP