Jascha-M

I see traces of white flaky dust-like particles settling / blowing from the air vents and accumulating on filter surfaces /cabin housing and surrounding areas of the trunk ventilation system. I changed the cabin / pollen filter elements which were rather clean otherwise and vacuumed much of it out but see it again (after running the AC). The previous owner had the AC completely refurbished (including evaporator, etc).The particles / powder (show glitter) are white in color but a bit chunkier than real dust.

Thanks much for any hints / suggestions offered ...?

Jascha-M

Btw, the p-car (1995 993 C2) sat around and stored for protracted periods of time by the PO. I noticed a substantial amount of the 'white powered-dust' on the inside of the air ducts. It looked to me like aluminum (or engine fan housing magnesium) oxide and so I wonder if it could be remnants of corrosion from the old air conditioning evaporator that was replaced as noted above...

pp000830

Jascha,
Testing the debris flakes:
Aluminum oxide is white and probably rigid and not soluble in water. A good test to see what it is.
If it is flexible and melts and burns with plastic smell then it may be failed insulation or other plastic debris in the system.
Finally, it could be water minerals built up in the system forming flakes, although I don't know how. These could look like Aluminium Oxide but are somewhat dissolvable in water.

Just some thoughts from a shade tree lab technician.
Andy

Jascha-M

Thanks Andy— collected (trapped in the filter elements) enough and was planning to do some chemistry today... it looks like magnesium oxide (which is ‘safe’) and should be soluble (used in water pH treatment and as a health supplement). Hard to explain how it gets in the HVAC system. The p-car was stored / garaged in a barn and shows sign of engine fan housing corrosion (probably magnesium oxideresidue) but not in the amount I collected (?)

Jascha-M

Nope— the particles are not soluble in water or 70% isopropyl alcohol... under magnification, appear crystal-like thin opaque sheets - glad the cabin filter was the first-line of defense / barrier.

I wonder if they had it stored with silica-gel humidity (mildew) control desiccant material or some such things (?)

pp000830

If it is minerals that precipitated out of the water that got in the system from say washing the car from a hose the crystals should dissolve in a weak acid like vinegar or a cleaner used to remove water scale from a shower of other plumbing, something like CLR (Calcium Lime Rust Remover).
Andy

JAB12

Hello @Jascha-M Did you find what was causing this problem and what did you do to resolve it? Curious about the preventive measures as well. Thank you.

Jascha-M

Vacuumed thoroughly all the remaining residue from the cabin filter canisters and fresh air intake ... PO had a full AC restoration including replacement of the evaporator so I assume it was ‘left behind’ since then ...(have not seen much of it again)

JAB12

So what are the flakes? Old insulation? did you replace the cabin filter as well? Thanks for the quick reply.

notabot

Looks like fake snow used for Christmas displays.

BobbyT

It might be helpful to look inside the ducting around the evaporator by removing one of the cabin air filters and shining a strong light in there.

But I wonder how this stuff got to where it is in the frunk. Air from inside the HVAC isn't blown through the frunk.

If this mystery stuff is coming from the outside of the car, then the route into the HVAC would be the fresh air intake in the exterior cowling just in front of the windshield wipers.

Flocked Christmas tree stored in garage overhead? (That's where mine is).

Jascha-M

Thanks for the many cogent ideas and possible entry points to consider —

Yes, I changed the cabin filters and found large amounts of the ‘snow flakes’ in the crevices of the elements and HVAC housing (see example photo of the unit and various air entry points)...PO told me that he stored the p-car in a converted barn but no clue otherwise. I removed the floor boards but found very little of the flakes in the heating ducts and excluded engine-bay heating components from consideration

nk993

Your car might have a drug problem. Check it into rehab