Cabin air filter choices

[sejman]

I am getting ready to due 60K service myself and shopping for parts (plugs, filters, etc.). I have had good luck with eEuroparts.com with my other car (Saab 900SE Conv) - they specialize in Volvo, Saab, and BMW.

Their cabin air filter selection goes like this:

30676413
(detail)Cabin Air Filter (secondary)
secondary filter (with ECC)Behr (Genuine Volvo)$26.90$26.90 71059
(detail)Fuel Filter
up to chassis# 16633Bosch$17.90$17.90 9204626
(detail)Cabin Air Filter
main filterBehr$14.90$14.90 9204626C
(detail)Cabin Air Filter (Charcoal Activated)
main filterAftermarket$19.90$19.90
I wasn't aware that there is a "main" and "secondary" cabin air filters. I found the nice posting how-to on the cabin air filter that is under the glove box area (I assume that's the "main" filter) - but what's this "secondary" filter all about. Also - I have a 2001 XC70 with the dual zone climate control, in case this matters.

[Art]

The secondary or multi filter referred to has additional charcoal compared to the regular pollen filter. It forms part of the IAQS (internal air quality system) in conjunction with a sensor to monitor and automatically shield the cabin from extraneous odors.

I haven't taken a close look at my own housing recently, but I believe there are two openings. A narrow one for the standard pollen filter and a wider compartment for the multi-filter which would also require the sensor to function correctly.

[sejman]

Sounds like the main (pollen) filter is the one that is doing the heavy work and is more important to replace. Is this a fair assessment?

Any opinions about which of the two main filters I should buy - Behr (I think is OE) or the aftermarket with activated charcoal?

[Willy]

If I am not mistaken, there is only one filter in any given car.
The multi filter if the car has IAQS, the pollen filter if the car doesn't have IAQS.
You have to replace the filter in accordance to your car having IAQS or not.
As Art already mentioned, there is a slot for each type of filter.
Willy

[Art]

Just to add to Willy's comments, both filters will provide adequate relief from particulates, but the multi filter and sensor combine to combat odors from contaminating the cabin. More details here.

You can use either of the two filters, but not both of them together. The multi (charcoal activated) version requires the sensor to operate the IAQS’ air intake.

[sejman]

Interesting - IAQS, huh? How do I know if my car is equipped with this feature so I know which filter to buy?

I assume that the more expensive "Cabin Air Filter (secondary)
secondary filter (with ECC)Behr (Genuine Volvo)" is for the IAQS system, and the other two cheaper "Cabin Air Filter - main filter" are for the "normal" cars - right?

Thanks for you help on this!

[Art]

I guess the easiest way to tell whether or not your XC is equipped with IAQS is if Manual/Automatic is on the air recirculation button.