Adding a cabin air filter.

Okay – so the air handler in our H2’s have a slot for a cabin air filter. But…… only a very very few of the very first of the 2003 models actually have it accessible. I have only ever seen one picture of the lid that the H2 ones came with an they are simply not available anywhere, period. This is the same issue on full size GM trucks and SUV’s as well. On the trucks they had a removable panel on the 99 through about 002 models. Then GM decided it was not needed and did away with it.

A cabin air filter IS needed and GM did not do away with the place in the molds for the lower air handler casing. But you have to physically cut the slot open. On the GM trucks and SUV’s you can get a GM or Dorman filter cover to close the filter slot up but no one makes the slot cover for the H2 that I could find. There are two types for the trucks and SUV’s and I have tried both and neither fit correct in our H2’s. It is however easy enough to make your own. Even on the trucks many just close it with duct tape and just replace the tape when they replace the filter. Since I have both of the truck style panels, I sort of fabricated them together to make a closure. If did not have those I’d have bent a piece of aluminum to fit or simply used some good quality duct tape (like Gorilla).

When you are under there you will be able to see the molded in line to cut the slot open. You can use a sharp utility knife (a few passes will get through it). The slot is an L shape and there is a plastic boss for a screw for a lid.

Anyways this is the filter I used.
When I cut mine open, the amount of crap in there was shocking. Tons of bits of leaves and dirt fell out on my floor. I spend 10 minutes with a shop vac and a small piece of tubing I taped to the vac hose to vacuum the rest out. I also ended up pulling the blower motor which is right beside there (I think it was 3 screws and it just drops out of the bottom) to allow me better access to clean the inside of the air box out better with a rag and to better vacuum all of the crud out. Also pulled the blower resistor out – even it had leaves and crap all in its heatsink….

Anyways a few pics. You can see all of the crap on the floor as well as on the evaporator coil. I used a long thin tube brush to clean the crud off the evap. In the last photo you can see the cover I made using both of the GM truck and suv type covers with a long screw to hold it. Not very nice but does work. Using the short L part of one cover and the long part of the other and had to add a couple of screws at the very back to support the long part. Duct tape would literally be far easier. Also attached is a PDF from GM on doing this modification on the later trucks and SUV's.

 

Thanks for sharing this, you covered the topic very well and as you say the it truly is needed give the amount of debris.

What was GM thinking?

If the blower motor controller is dropped out, can you see how much debris is in there and possibly clean it out as a stop gap measure?

 

Nice work! Except, the cabin air filter in a vehicle helps remove harmful pollutants, including pollen and dust, from the air you breathe within the car.
Inserting a filter with all the debris collected there, will reduce airflow in no time.
Now that you have an access panel, I recommend a couple things I multipurpose:
Dryer Vent Lint Removal Kit
High-Density Rubber Foam Weatherstrip Tape

 

I think the slot for the resistor would be too small to really get to anything. The blower itself would give much greater access to reach in there though and is also fairly easy to remove.



The skinny brush in that lint kit is sort of like what I used to help brush the crud off of the evaporator. I also used a spray can of AC coil cleaner and sprayed it down, let the foam soak in on it for a few minutes, brushed some more, then sprayed some more. I ended up leaving it sit for a couple of hours to dry back out well.

The slot covers parts I used to close the slot up do have a foam rubber seal on them so I'm good on that front. Duct tape instead of a rigid cover would also make for an effective seal.

Another thing I did prior to this mod (when I was doing my headliner and getting the windshield replaced) was to screen the air intake under the cowl. I used some fairly stiff aluminum screen and bent it to fit nicely over the cabin air intake to prevent any sort of leaves or anything in there in the future. The black tape was temporary to secure the screen while some silicone around the edge cured. The cabin filter is a huge benefit here where I live in the southeast as we get a ton of pollen in the air this time of year and during some of the hot summer months when we have an extended dry period there can be quite a lot of dust in the air, particularly if off road or on dirt roads which I frequent am in the rural area I live.

You can also see quite a bit of dirt on the blower wheel in the below. When I dropped the blower out from the inside I also cleaned the blower wheel up as well before putting it back in.

Also updating to add - I forgot that there was another old thread on this. Apparently there are a few variations of the airbox. One I can say with certainty - the GM truck/SUV cover panels for a 99-02 and the ones for 03-07 do not fit the slot on my 2003 H2. I saw in that thread someone saying it is not needed if there is no dust in your H2. The fresh air intake is under your cowl panel and there is zero filtration. If your H2 has ever been outdoors then dust has come in, period. Seems unlikely by leaves and other bits of debris will also make it under that cowl panel and into the blower. If you have ever cut the air on and heard any sort of rustling noise, that is most likely some leaf bits in the blow getting chopped up.