dark specs coming out of a/c vents

[pamoor21]

I have a 2002 Monaco Exec. Just recently, when I run the a/c in fan, a/c, or heat pump, i get small flecks of paper thin size of a dime coming out of the a/c vents. Any idea why ? It is driving my wife crazy, thus driving me crazy. Any ideas. Thank you, Pat & Jan

[DavidL]

The AC units are open to fresh air on the roof.  Small particles could find there way into the ducts.  There is no filter on the incoming on mine.  There are only filters on the AC intakes.

Or, it could be the plenum degrading...all depends on what you are actually seeing...dead decomposed leaves?

If it's that bad, you could vaccuum out the plenum via the outlets, take the covers off the AC units and clean them.  The AC condenser likely is full of dirt and would love to be cleaned out as well.  I powerwashed mine (very carefully).  I closed off the intake plenum opening and went to town.  Now spanky clean.

Edited January 15, 2021 by DavidL

[Bruce B]

I had something similar occur so I removed the filters in the ceiling and washed them.  The foam was old and degrading so I have since made new ones.

[bobdinsmore]

I find occasional (about half a dozen) black flecks and styrofoam flecks falling from the ceiling ac vents in the bedroom only after the motorhome has been unused over the winter. The black flecks appear to be very thin plastic/mylar which could be a covering off insulation. The ac has not been running for months when these show up so I'm guessing they are from mice because I catch one or two a winter. I just get the mice and clean up the flecks.

[Mel S - '96 Safari]

22 hours ago, DavidL said:

The AC units are open to fresh air on the roof.  Small particles could find there way into the ducts.  There is no filter on the incoming on mine.  There are only filters on the AC intakes.

Or, it could be the plenum degrading...all depends on what you are actually seeing...dead decomposed leaves?

If it's that bad, you could vaccuum out the plenum via the outlets, take the covers off the AC units and clean them.  The AC condenser likely is full of dirt and would love to be cleaned out as well.  I powerwashed mine (very carefully).  I closed off the intake plenum opening and went to town.  Now spanky clean.

DavidL

RV roof a/c units don't draw any OUTSIDE AIR into the coach. 

The Room Air Blower draws in ONLY INSIDE AIR and blows out recirculated/cooled INSIDE AIR, (as seen in this illustration)

[DavidL]

Agreed Mel, go take your AC cover off and see how much junk is in it.  That's my point.

The design of the AC rooftop units are pretty unsealed externally.  There is just a little piece of foam (that degrades) "sealing" interior to exterior air.    And the interior air constantly circulating has dirt in it too.  Every condenser I have looked at that is a few years or more old are gross.  Rewarding to clean them and know they are clean and efficiently cooling / heating the air.  On my 2002 (newer to me) the condenser was almost completely blocked with debris.  Looked like mud.

 

Good time to reseal the fan units as the HVAC tape they use is commonly flying off in the breeze...which could be the flakes the OP is seeing...Clean it and retape it to reseal.  HVAC tape at Home Depot is like $8.  Might as well get some foam from the door sealing aisle while you are there to replace the old degraded foam.

Edited January 16, 2021 by DavidL