Cabin air question

[DubyaO]

Hi folks,

I just installed the Bosch cabin air filter w/o problems. But something came to mind: Does this filter only filter air when you have it on Inside or on Outside air circulation? Or both?

The reason I ask is that I can't really tell any difference. Furthermore, with it in the Outside air position, I can still smell exhaust and other noxious fumes from the highway...whoopie! :(

Any insight would be 'preciated!

DubyaO

[southpawboston]

it filters both fresh and recirculated air. but don't expect it to filter out fumes. it's just a paper filter, it's not a HEPA filter capable of filtering sub-micron sized particles. but it's good for filtering dust and leaf debris!

[cclngthr]

I wish they had a hepa filter that was the same size.

[southpawboston]

yeah, a HEPA filter would be nice, but HEPA filters also cause more resistance to air flow than a cheap paper element, so the fan would not blow as effectively. even with the factory filter, i noticed a drop in air flow, equivalent to about one setting level on the fan knob.

i picked up a three pack of carbon-impregnated pre-filter sheets, designed for home air conditioners. these pre-filters trap a lot of dirt when used on my home air conditioner, but don't cause significant resistance (they're sort of the consistency of household green scrubbing pads). i was thinking of laying one sheet on top of the stock filter next time i change it. that MIGHT help remove some odor from the incoming air, but i doubt it will remove more than a small fraction. but as an inexpensive pre-filter ($13 for enough to make six cabin pre-filters), it may double or even triple the life of the expensive ($35) OEM cabin filter.

[cclngthr]

A carbon filter also can eliminate most contaminates and might even replace the paper element. I have a indoor filter in my house that uses a carbon filter and it can trap most contaminates. Some can be washed out as well.

[Roydjt]

SPB, can you please give the measurements (LxWxH) for the filter? I want to go to Home Dept and make one, but I want to know which to pick so I can do as little trimming as possible. Thanks!

-Roy

[Onelove5683]

can u basically just cut any filter material to size and put it in there?

can u get a hepa filter and cut it?