Air flow direction for Mann cabin air filter?

[LVP]

Originally Posted by ants_oz

To those who think the filter is installed correctly - that air enters from the top and flows down past the filter. I suggest you check your facts.

Air flows in from the plenum UNDERNEATH the filter - that is why all the leaves etc collect in the bottom of the plenum. Air flows UP through the filter, and into the interior ducting.

Take the unit apart and check it if you don't believe.

On the attached diagram, air flows IN via the grilles (left and right) indicated approximately by No. 14 (for the right hand side of the vehicle). Down via the deflection ducts indicated by no's 5 and 6. This directs the inlet air down from the grilles, UNDERNEATH the filter carrier/plenum roof (no 3). The floor of the plenum (no 1) is where leaves etc collect.

Air then flows UP through the filter, into the main plenum (no 3), and out the back through the sealed openings (seals are no 11) into the vehicle interior ducting and heater radiator (etc).

Yes, yes, yes. I just went to look at mine. Bottom side of filter is full of crud. Air flows from bottom to the top. Arrow goes UP.

[mistermetoo]

+1 arrow goes up. took a while to figure it out

[StephenVA]

Originally Posted by ants_oz

To those who think the filter is installed correctly - that air enters from the top and flows down past the filter. I suggest you check your facts.

Air flows in from the plenum UNDERNEATH the filter - that is why all the leaves etc collect in the bottom of the plenum. Air flows UP through the filter, and into the interior ducting.

Take the unit apart and check it if you don't believe.

On the attached diagram, air flows IN via the grilles (left and right) indicated approximately by No. 14 (for the right hand side of the vehicle). Down via the deflection ducts indicated by no's 5 and 6. This directs the inlet air down from the grilles, UNDERNEATH the filter carrier/plenum roof (no 3). The floor of the plenum (no 1) is where leaves etc collect.

Air then flows UP through the filter, into the main plenum (no 3), and out the back through the sealed openings (seals are no 11) into the vehicle interior ducting and heater radiator (etc).

:thumb up:

[babyduke]

Yup. Held a piece of tissue paper inside and it blows upward toward the windshield.

[JAX01X5]

If all else fails a diagram says it all

[X5only]

Originally Posted by ants_oz

To those who think the filter is installed correctly - that air enters from the top and flows down past the filter. I suggest you check your facts.

Air flows in from the plenum UNDERNEATH the filter - that is why all the leaves etc collect in the bottom of the plenum. Air flows UP through the filter, and into the interior ducting.

Take the unit apart and check it if you don't believe.

On the attached diagram, air flows IN via the grilles (left and right) indicated approximately by No. 14 (for the right hand side of the vehicle). Down via the deflection ducts indicated by no's 5 and 6. This directs the inlet air down from the grilles, UNDERNEATH the filter carrier/plenum roof (no 3). The floor of the plenum (no 1) is where leaves etc collect.

Air then flows UP through the filter, into the main plenum (no 3), and out the back through the sealed openings (seals are no 11) into the vehicle interior ducting and heater radiator (etc).

Oh-oh, so I've been installing mine the wrong way all these years! I went out and fixed it. Your diagram makes sense and I could clearly see the filter sits in front of #11 holes. It's now obvious the arrows pointing up towards those holes is the indeed the correct way to install the filters. It even fits better this way than before.

Thanks for the clarification!

[upallnight]

Does it really matter? Air will still flow if you have the filter installed wrong.

Is there a right side to wipe your ass with the toilet paper?

[ants_oz]

Originally Posted by upallnight

Does it really matter? Air will still flow if you have the filter installed wrong.

<snip>

Actually yes, it does matter.

The reason being, this is a 'loose fit' concertina filter. The concertina has to be placed so that the ends trap air and seal against the housing sides. If fitted incorrectly, the concertina can be compressed by the airflow instead of expanded to fit the ends of the housing, resulting in substantial air leakage around the sides of the filter matrix.

[X5only]

Originally Posted by upallnight

Does it really matter? Air will still flow if you have the filter installed wrong.
...?

I think, yes, and for the same reason I'm required to install correctly the air filter of my houses' heating and air conditioning system. The filters have directional install arrows and are therefore made with the intention that air flows in one direction through the filter medium. The filter cannot capture dust particles as well when air moves through the filter in the wrong direction. That unwanted debris would end up floating in my home’s air instead of being trapped by the filter. The dust on the road is more, and therefore even more critical that correct installation is done for autos.

[cn90]

@X5only,

For the sake of discussion:

- Home HVAC air filter has a metal mesh on the downstream of the filter b/c the blower is very powerful (about 1/3HP or so) and can (and will distort) the filter element. The metal mesh is there to catch the paper filter from flying apart etc. So directional installation is important.

- Re E53: the above direction is correct (i.e. the arrow points in the correct path). However, the arrow is not that critical in the car b/c:
a. The blower is weaker than the home blower.
b. No metal mesh.

BTW, the filter element is non-directional, you can blow air in either direction and it will trap dust particles anyway.

Now the academia is over, we can drive the car and enjoy it...