What is proper function of RECIRC in W124
 

I just replaced my evaporator and all the vacuum pods in 1991 300E.

It seems to want to run in RECIRC mode all the time (80%). When I change to EC it goes to fresh-air mode.

Is the function of the RECIRC switch only to go the last 20%?

Does anyone know exactly how this is supposed to work? RECIRC is great except that the air can get a bit stale sometimes.

It will pick the resirc mode based on outside / inside temp. If they are different enough it keeps the resirc going. The switch will take it to 100% for 20 min no matter what mode it was in before, then 80% after that.

-Jason