Recirculating AC air and pollen filter

[Benzy]

Hi, new to the site. I hve got a 96 C220 and I have some AC queries. In my docs have a ac user manual from diavia brand. Why is it when the recirculation button is pushed (lit) it only stays that way for 5 mins and then reverts to outside air (not lit)? Can we chg this setting? It seems odd to me that when other car makes recommend operating the AC with recirculation air always in order to retain coolness insde the cabin and tax the compressor less, MB does the opposite and as a reslt isnt at all cold like the other makes. Also when it is lit, the smell in the blown air is kinda musty. I have removed the pollen filter and given it a good vacuum but still the same (if slightly reduced). Is it possible the pollen filter hasnt been chged in 10 yrs? Is this a service item that should be changed now and if so at what future periods?

 

[jberks]

Hi,
I've never heard of running in recirc mode to take the pressure of the aircon. To be honest, it sounds like an old wives tale to me as on a hot sunny day, the air inside the car could be rapidly heated to temperatures above the outside air temp so you're better off with cooler fresh air. The aircon system should be big enough to cope with normal requirements. Certainly mine is quite capable of freezing me on a hot day. The reason they put the timer on is because MB decided that the air would be stale if left to recirculate too long and could cause drowsiness. The Recirc is simply supposed to be a way to stop temporary bad smells and fumes e.g. a truck in front or agricultural odours from entering the cabin. Once the source of the problem has gone, you are supposed to switch back, but if not, it will do it for you after a period. So, no it can't be bypassed.
Your lack of cold air has probably got more to do with your aircon system needing a service / recharge and possibly, as you suggest, the need for a new pollen filter to allow a greater airflow.

 

[Benzy]

I need to chk the books if pollen filter has ever been chged. AC sys completely serviced with recond compressor, new gas, drier, tx valve, seals, oils, so except for pollen filter its at optimum (orig condensor tho has been cleaned with pressured air when mech replaced new radiator). Like some other posts side vents very subdued compared to other makes. Is it usual at this age perhaps the evaporator and heater matrix be clogged? Pls advise.

 

[C220GJS]

Change the pollen filter, should be changed yearly but is extra to normal service on most cars and is often missed, easy and cheap to change.
Geo.