[AZSobo]

I noticed the last time I changed them, the old filters have blueish stains on them. I'm not sure if maybe foam from the carwash is getting in the fresh air intake or if it's something else. Sadly this is the first vehicle I've owned that has cabin filters so I can't look back at prior experience. The filters I've been using are TYC, they're inexpensive and I change them every 5000 to 7500 miles, we live in Phoenix, filters get dirty faster with all the dust.
Thanks

 

[Skibane]

Could also be residue from windshield washer fluid.

 

[m_bisson]

Got any pics?

 

[2013Pro4X]

Mine are usually just black, but I like the theory above regarding washer fluid.

 

[93hardbody]

I'm not sure how they work on this truck, but on most vehicles the filter only works on recirculate- they don't filter fresh air. If they are stains, and not blue dust (?) then somehow liquid is spilling into the filter . . . did you loan the truck to a couple of smurfs?

 

[OutFrontFrontier]

I've ran the TYCs in mine changed annually. Never had one come out blue though. Its not far fetched to think some wash fluid got down there if the truck was parked and someone hit the juice with fan on hi?

 

[shift_RUSH]

I'm not sure how they work on this truck, but on most vehicles the filter only works on recirculate- they don't filter fresh air.

Not sure if the above statement is correct...for Gen 2 Frontiers.

~ Nissan's description of 'in-cabin microfilter' -> "Replaceable air filter reduces the amount of pollen and other particulate pollution that can enter the passenger cabin."

I very rarely run my HVAC on recirculate, and can attest to how filthy the filters were when I changed them after 20k miles.
.02

 

[smj999smj]

Our filters work on both fresh air and recirculated. That said, I've never seen blue stains on them. I also make it a practice to shut the truck off when I get it washed. You might try making sure the HVAC system is turned off the next few times through the car wash and then pull the cabin filter out and see what it looks like.

 

[raine]

I'm not sure how they work on this truck

Could have stopped right there lol j/k

Yeah, 2nd gen all the air goes through the cabin filter - both fresh and recirc.

The theory of washer fluid is suspect only because any liquid from the OUTSIDE of the truck won't just drop right onto the cabin filter. All the fresh air for HVAC has to go through the LEFT side vents in the cowl, travel from the left to the right side of the vehicle in an air channel under the cowl, then up and over a large metal lip before it gets to the cabin filter.

Then again people have had rats make it to the cabin filter... maybe @93hardbody 's Smurf theory is more plausible LOL

 

[smj999smj]

I wonder what year the Frontier is? I don't know if the Frontiers were subject to it, but I kinda remember some of the early R51 Pathfinders having an issue with rain water getting into the fresh air inlet under the cowl and I'm pretty sure there was a TSB on it.

 

[AZSobo]

I forgot to come back and update:
After finding that blue on the filters, we quit running the a/c in carwash or until after we've hand dried it in nearby parking lot - killer in the middle of Phoenix summer.
The last couple times I've changed them, they were dirty but not blue so thinking it was the car wash soap working its way to filters. Maybe this will help someone in the future if they notice same problem.

 

[Skinny06]

Forgive me for having no clue. Where are our in cabin air filters?

 

[2013Pro4X]

They are located behind the lower glove box. There is a thread somewhere on here on how to change them but I can’t find it right now.

 

[smj999smj]

Be careful not to break the plastic tab on the case that the door latches onto. Here's a video on it:

 

[Nissan4Life]

I think I have seen a blue paint or stain on new paper filters before. Thought nothing of it. Can not recall what it was for. Air filter, house HEPA filter??

I broke my door tab the first time I change out my filter. There is a handy bolt hole though. I put a bolt and somehow got a nut on there. This is a terrible repair as it makes it near impossible to remove. I now just use a zip tie that I cut off every time I change the filter.

 

[bajasam]

either coolant or wiper fluid spilled from windsheild area, nothing to worry about.