Cabin Air Filter for Jeep JK 2013

Cabin Air Filter
We never paid any attention to the cabin air filter in our previous cars. Maybe there was one there and it got changed during the regular service intervals, or not. We got aware of the filter after the Jeep was in for a service. They confirmed with us before they changed the filter, and that was OK. The cost of the filter and labour was something where we could save some money, at least twice a year. And this is how this project started.
The 'Before' and 'After' are reasons enough to actually change the filter. Yes, we know, the filter is for the birds when the windows are open and the doors removed. But think about winter with the salt dust in the air, spring with the pollen and all the other times when we drive on dusty forest service roads. We don't always have the windows down, too many biting and blood-sucking insects.

A new filter from MOPAR is $12 (Part # 68233626AA) and works OK. For the BOSCH 6009C HEPA, you pay about $36 or more. For less than $20, we get the Filtrete 2200 from 3M. We get 8 Jeep filters out of one 3M Filtrete 16 x 25 x 1. These filters have a wire mesh on both sides, watch your fingers.
We used the original MOPAR filter as a mold and built a frame around it. We should have reduced the size by a hair. Some of our models have a very tight fit.
The dirty filter on top was one of the initial prototypes where we used a cheaper furnace filter. We put this one in before our trip to Whistler in 2020. The dirt you are looking at accumulated over less than 15,000 km during September and October. The new 3M filter will stay in the unit until March, just before the pollen season starts. It actually works. We had one this spring and I did notice the difference in the Jeep.

Instructions for the DIY Jeep JK cabin air filter
1. Get a 3M Ultra Allergen Filter for about $20 or less.
2. Use the original filter to make a wood frame
3. Cut 8 squares from the 3M filter, or 6 without problems
4. Cut thin cardboard into stipes to make the filter frame. Make them as long as possible
5. Put some wax (or baking) paper inside, so the glue (filter) won't stick to the wood frame
6. Line the inside of the frame with the cardboard strips
7. Put the 3M filter square inside the wood frame
8. Glue all the sides. Use plenty of glue to seal any open gaps
9.Replace the filter in Jeep with this $3 filter for the next years. We change them for every new season

But this is not whole story. Where there is an air filter, there must be a fan.

Replacing the blower motor
It was February 2019 and it was cold. We spent the weekend in Sudbury and the temperature during the day was -10C. When we got up to return home, the engine started fine, but not the blower motor. Some awful squeaking noise and no air movement. There was plenty of hot air from the motor, but it never made it into the cabin. Further south, when we reached a more moderate climate like -5C, the motor started working again.
We didn't replace the motor immediately, it was working OK again. In fall of 2019, we ordered a new blower motor from a 3rd party and agreed to a non-MOPAR version. All was fine until we found out that the plug was not the same. Out with the new and in with the old. We returned the motor and got the MOPAR version. More expensive, but no hassle to replace.

The steps to replace the blower motor are simple. Disconnect both cables, one for the light, one for the motor. Three screws hold the motor in place. Change the light and control unit from the old motor to the new. Up goes the new motor, tighten the three screws and voilà, it is humming again. Click the image to get a closer look at the unit.
There are plenty of good how-to videos that cover this topic in more detail. But none of them pointed out the problem with the connector plug that may not fit. Anyway, we hope you don't have to ever replace the blower motor, but if you do, make sure you get the one with the correct connector adapter.

Air Filter ratings
The 3M Filters use MPR (Microparticle Performance Rating). The 2200 MPR is equivalent to MERV-13 (Minimum Efficiency Reporting Values). MERV is a more universal rating. The chart shows the values for the filter we are using. A list for all levels is available at EPA.
We are using the filter in a Jeep, so many of the examples we find do not apply to road or offroad conditions. When it comes to dust or wildfire smoke, some particles are so small that they don't get trapped in the filter. As a general rule, the faster the dust settles, the bigger the particles. The wildfire smoke particles are very small and for this reason they can travel over long distances.

We have no illusions, anything smaller than 1 micron will not get trapped. One micron, or micrometer (represented as µm) is 1000 times smaller than a millimeter. The same logic applies to the Tire Dust, Brake Dust and Road Salt. You can find multiple studies about tire and brake dust and the findings are not very encouraging.

When it comes to pollen, I know for a fact that the filter works. I have made it through several Pollen Seasons already and could breathe much easier.

If you decide to create a HEPA filter for the Jeep, you may want to do some research on the air flow. The blower motor may not have enough power to pull the air through, or the flimsy jalousie may collapse when the outside air is pulled in. To take advantage of the HEPA filter, you may also want to take more care in the construction of the filter frame.