SOLVED - Front Chassis HVAC Blowing Black Snowflakes

[Tom Cherry]

I checked with the last of the esteemed founders and he has been posting here since Bill D started it.  He laughed....."That's a NEW ONE".

Was out on the road for almost 3 months in 2018.  Rig sat in storage in 2019 due to health.  Have been out about 4 times for several days this year.

Brought Camelot home from storage.  When we left home, noticed some black "flakes" on the carpet.  They were thin.  Anywhere from maybe 1/4 postage stamp size on down.  If you have ever had the vinyl or leather on a fold over cover or notebook peel off....that is what I looks like.

Best I can tell.  Front HVAC fan was set to ON.  Did not need it for a little bit, so the Mode Control was in the OFF.  Switched it to Max Cool.  Then a few more flakes blew out.  Looks like it is coming from the lower left (road) vent on the Driver's side.   That looks like it happened about 3 or 4 times.  Stopped.  OK....settled in.  Got curious.....thus my trouble shooting and the comments and the question....

NOW....as a point of interest....and many more folks probably have discovered this.  My Camelot has TWO vents under the driver's feet.  The left one has a swivel outlet that you can push forward and throttle down.  It is WAY up on the firewall.....never realized it.  THEN....the the right one has a slide switch or tab so you can shut it off.  You can also change the direction of the air flow.

Upon more careful exploration, The vent bezel on the dash is actually threaded on.  So, if you unscrew it, the rear pipe, which has the rubber hose on it, will come off.  I was able to get that out.  I have turned on, several times (using the ignition switch), the HVAC so that it  comes on in HIGH.  Nothing blows out.  No flakes.  I have picked up about enough flakes for maybe a 1" or slightly larger square of the flakes.  Probably had 15 flakes from 1/16" to 3/8" irregular.  Only one or two large ones.... 

The flakes are a textured vinyl on one side and then seems to have a film (adhesive) on the other side.  They are NOT the same material as the rubber hose (with the plastic spring inside).  My FIRST thought was that the rubber hose was disintegrating  (falling apart).  Nope....the rubber hose is thicker.  These pieces of vinyl (?) are much thinner.  They are brittle and break when you pick up or touch them.  Think dry brittle tissue paper.  Or, again the thickness of a thin plastic baggie.

I DID find that Monaco would "cut and splice" the hose if it was too short.  So, I have a splice in that line.  They just pushed one end inside the other and sort of twisted and the springs meshed like a nut and bolt thread.  I am reluctant to force compressed air into that line.

OK....final test.  With the hose removed and no kinks or binds (I can see about 4 ft of it, I cycled the ignition on and off.  With the fan on HIGH and every vent closed....save the open hose....NOTHING.  NADA...  I have switched the HVAC to every position from VENT to DEFROST to MAX AC (recirculate).  With the fresh air intake open.....nothing.  With it closed (recirculate)....nothing.

That's as much info and experimentation as I have done.  

FIRST.....has anyone else ever experienced this?  If so....then did it stop or whatever....

IF it got worse, then how did you (assuming you did) fix it?

I can NOT visualize or conceptualize a plenum with a Vinyl coating in the air handler....but I am NOT an auto HVAC guy.

Thanks....other than that.....life is great.....might need to get a dustbuster and just keep cleaning up until it is so bad that I go further.

[Ernest Tumbleston]

I had something like that years ago in a car or truck. It was from some moisture that puddled in the bottom of a hose, grew black mold, dried out, flaked up and blew out the vent.  I don’t know if this is your case.  If you fingered them on the seat, they looked like soot as they broke apart.  

[Tom Cherry]

1 hour ago, Ernest Tumbleston said:

I had something like that years ago in a car or truck. It was from some moisture that puddled in the bottom of a hose, grew black mold, dried out, flaked up and blew out the vent.  I don’t know if this is your case.  If you fingered them on the seat, they looked like soot as they broke apart.  

Thanks for the prompt response.  These flakes are a bit "harder", but still brittle.  If you press on them against a hard surface or the palm of your hand, they will crack down the middle, but they don't dissolve.  One side has a decided "Vinyl or faux leather" texture and the other side has a light residue.

I don't think that is mold, but I hope that whatever flaked off has stopped.   Beat goes on....  I guess that after I reassemble and drive a while we will know...

[jbret06]

Hello Tom,  I  sure wish I could shed lite on this problem as I  have this exact problem  on my 2008 Knight. I've  had the  problem for over a year now and haven't been  able to figure out the problem.  The amount of flakes that  blow through has decreased quite a bit but there are still a few small flakes that blow out.  I really can't tell if this problem  is affecting my cab ac air flow or not.  Overall, my cab ac only rates about a 'C' grade.  I'll sure be interested to  see if someone  else has a fix for  this  problem.  Thanks,

Jim  Bradley 

2008  Knight, 38PDQ

 

[Tom Cherry]

1 hour ago, jbret06 said:

Hello Tom,  I  sure wish I could shed lite on this problem as I  have this exact problem  on my 2008 Knight. I've  had the  problem for over a year now and haven't been  able to figure out the problem.  The amount of flakes that  blow through has decreased quite a bit but there are still a few small flakes that blow out.  I really can't tell if this problem  is affecting my cab ac air flow or not.  Overall, my cab ac only rates about a 'C' grade.  I'll sure be interested to  see if someone  else has a fix for  this  problem.  Thanks,

Jim  Bradley 

2008  Knight, 38PDQ

 

Well,

At least for me, the good thing is that I have a LOT of air (the HVAC SYSTEM....LOL) coming out.  I have not noticed any drop in air flow.  Quite the contrary, it seems to be doing fine.  I have to top off my Freon Charge about every two years.  I should do it myself, but I let the shop that does all my regular service just "Charge 'ER up..."

I did shut off the two foot vents in the driver's area.  I never knew they were there.  With the AC, I want all I can get.  I also never run it on anything but Max Air.

NOW....here are some tips that I have learned.....some I get credit for and some I learned...

COOLING.  2 AC's are NOT enough for a 41 Ft MH....  I doubt that the foot reduction does much to help your overall cooling.  I'm talking the Roof Top's since the whole think, when I travel, is interrelated.

When the temps outside are below say 85 dF, I can usually do OK with the Front HVAC.  That is contingent upon having it properly charged.  When it gets much above that, I switch to the Roof Tops.  I think that the fuel usage for the Genny is actually less than the compressor on the engine.

NOW....the BEST thing I have ever done was put in a small recirculating fan.  I'm talking a cheapie.  Maybe a 8" - 12" oscillating one.  I have a 5 pound Dumbell weight attached to the base with a Bungee cord.  I sit it right between the Co-Pilot and the Pilot's seat.  Sort of aimed upward or maybe 20 degrees.  I let that puppy push air.  That cools the front compartment and I drive with no issues.  NOW, if it is 95 or so outside, I may turn on the front HVAC to supplement.  But that is usually a 15 minutes on and 15 minutes off.

I also run that fan in the living area during the hot (> 85 dF outside) days.  Just keeping the air moving and stirring is great.

The OTHER trick (assuming you keep your filters washed) is to set the rear AC about ONE degree HIGHER than what the front is.  At Bedtime, I switch the rear COOL FAN Mode to LOW.  That keeps the air handler running and it keeps the rear from getting stuffy.  My wife has been known to make some noise as she sleeps....so the white noise of the blower allows me to drift off.  She says that it is a lot more comfortable and the bedroom stays cooler and less stuffy.

The OTHER trick for heating from the FRONT HVAC is to turn the system to MAX AIR.  Then turn the Temperature Control to HOT....or all the way over.  There is a "shutoff" built in so that the compressor does NOT run.  By running the Max Air setting, you get recirculation (sometimes humidity is an issue but not ordinarily).  Shutting off the incoming cold air really keeps the front cockpit MUCH cooler.

Frank McElroy also did some air checks on his front Cockpit (under and around the firewall).  He used spray foam and sealed all the air leaks.  He said that made a world of difference also.

The final trick and this was not needed for me was to take off the vents (the swivel with the louvers) and make sure that the duct is sealed and you are not losing air to the ceiling.  Monaco used two (maybe more) styles of plenums and some of the ducts were not sealed or properly installed.  You can pull the vent and get in there with a good light and see if there are gaps.

OH....I did also use foil tape in the housing of the two HVAC roof units.  I pulled down the white covers.  I made sure all the joints were sealed and such.

NOW....back on point....the BLACK SNOW FLAKES.  I have ordered a flexible line CellPhone (Tablet) inspection camera.  I am going to probe the hose and see if I can determine WHERE it is coming from.  I might find BAD NEWS....but at least I will know.  That will not be done for a while.

IF ANY OTHERS have the Black Snow.....Chime in.... at least I am NOT alone in the quest....

[Frank McElroy]

Tom - Have you looked at the fresh air intake door flap on the exterior side of your dash HVAC box.  It would be interesting to find out if you see any of those black flakes being sucked into the system.

Yes, when we were using our coach in freezing temperatures, it was really easy to find all the air leaks from under the dash and the control panel under the drivers side window where wiring enters through the floor.  When its freezing outside and your coach is heated, just turn on the vent fans.  It's really easy to find air leaks that way and boy did I have air leaks! 

If I recall correctly, it took a couple of cans of black spray foam to seal the air leaks.  Largest leak was the dash plywood up near the front cap.   This was an easy fix with the generator door open and through the side access panel below the drivers side window.   

Sealing these air leaks made a huge difference when traveling in very hot or very cold weather.

[Tom Cherry]

9 hours ago, Frank McElroy said:

Tom - Have you looked at the fresh air intake door flap on the exterior side of your dash HVAC box.  It would be interesting to find out if you see any of those black flakes being sucked into the system.

Yes, when we were using our coach in freezing temperatures, it was really easy to find all the air leaks from under the dash and the control panel under the drivers side window where wiring enters through the floor.  When its freezing outside and your coach is heated, just turn on the vent fans.  It's really easy to find air leaks that way and boy did I have air leaks! 

If I recall correctly, it took a couple of cans of black spray foam to seal the air leaks.  Largest leak was the dash plywood up near the front cap.   This was an easy fix with the generator door open and through the side access panel below the drivers side window.   

Sealing these air leaks made a huge difference when traveling in very hot or very cold weather.

Nope.  Have not looked at the exterior of the HVAC.  IF that is a Vinyl or plastic door, then that could well be it.  My first thought was it was like a thin film of undercoating peeling off.  But it has a texture....not quite stamped....but definitely not a molded slick one.  Will do that when I get home.  We are at Emerald Isle now.  

[Tom Cherry]

UPDATE.....Frank McElroy and I spoke and he asked me to revise this and include some pictures.  It appears that his 2008 Dynasty and my 2009 Camelot have very different Front HVAC boxes or plenums....based on our texting pictures back and forth....so I am editing this and including pictures.

Here is what I found.  The Black Snow is actually the plastic backing from a piece of foam insulation used across the firewall.  This insulation goes all the way from, as best I can tell, one side to the other.  However, there is a section or two where there is NO insulation as there are many lines coming out and Monaco just 'foamed around" them.  This insulation is a cardboard or fiber type.  It has a heavy fiber board surface, then a thin layer of foam and then a top film to prevent damage to the foam.  After 12 years, the top film is deteriorating and peeling away.  Most is gone....but there are some note card sized pieces dangling.  THAT film is what I THINK is in the interior or the conditioned side of the system.  

Interestingly, Frank's Dynasty does NOT have that material.  My firewall is steel (welded)....so I assumed that it was insulated for the obvious reasons.  THIN is the key operative.  I have poked and prodded and the foam is virtually a powder.  So, repair or replacement will be a challenge....but the film coating is the source of the black snowflakes.

There are TWO theories on how it got into the ductwork.  

Theory A;  IF you change the mode or the air flow circulation control while going down the highway and use any position EXCEPT Max Air, then there are TWO doors on the HVAC box that open.  They have a foam or hard rubber cover on the doors.  They seal against the inside of the plenum.  MAY be visible in the photos...  There is NO SCREEN or INLET FILTER on them.  So, if the film is flapping in the breeze and you have all the air currents circulating (while driving 65 MPH), you create Turbulence in the Genny cavity.  The HVAC Fan on HIGH is sucking in air.  So any road debris or such would be sucked in.  YES, Ideally, Monaco would have put on a fine screen or at least a 1/4" grip wire covering.  They did not.  BOTH of the inlet doors are wide open and will suck in anything.   SO, the deteriorating film MAY have gotten sucked in.

Theory B:  The MAY BE a raw edge of the foam sheet insulation that was "cut out" for the opening for the HVAC Plenum or External Air Box.  IF there is a small strip of the insulation that is cut a little long and hanging out INSIDE THE PLENUM.....then if that film starts to detach or deteriorate, it will be "Sucked" inside the air box when the fan is on....probably on HIGH.    If that is the case then, eventually, the film will self destruct or detach and the problem should be over.  It looks like Monaco used a large sheet on the Passenger side.  They just glued or attached it to the steel firewall and then cut out the opening.  They screwed on the back side of the HVAC (Plenum) cover, overlapping the interior edges of the insulation.  SO....in theory, that could be or maybe a combination of Theory A.  

At least, for me....I NOW think that I understand what MAY have happened.  I will try to find some suitable covering....maybe a foam board with a foil covering and clean (abrade) off the deteriorating foam.  Then cut sections to fit and spray on some adhesive and attach.  I will probably try to use some foil tape for the edges.  This is a WIP and I need to see how well a small section cleans up.  BUT, for the interim, I have peeled off the film.  The foam is useless, so that will eliminate any blown in film from turbulence.   MAY use duct tape or something to attach a wire cover over the two inlet openings .  The Doors are BEHIND and when they close, they push against the plenum housing.  I DID reach in there, with the fan on and in the Vent Mode and felt around.  I did NOT feel any debris nor were there any Black Snowflakes on my finger tips.

I DID clean up the Black Snowflakes in the cabin.  Based on where they were and under some stuff....i THINK that they were actually blowing out some of the Passenger side outlets.  My wife was opening and closing them and she said that MAYBE there was some coming from her side as well.  For whatever reason, the BULK of the debris came out the left driver's lower air vent.

I will try to run a cellphone inspection camera in the one hose and see if there is a residual or a small pile of the film in there. 

To Frank's point....his Genny cavity is totally different.  He has external hoses or ducts going up to the front defroster vents.  All MY ducts or hoses are on the PASSENGER side of the firewall....none exposed in the Genny Cavity.  Don't know, but also think his inlets are different.  He also has a HVAC filter on the inside.  Mine is plain Jane....

I DID look at some points for additional foam insulation.  There is a horizontal (plywood?) strip just above the wiper motor and linkage.  Mine has some foam....maybe 75%.  Franks was barely (25%?) foamed.  If you stick you head under or reach up with your fingers, you can see the front Gap.  Frank did some "air flow" testing and used his Fantastic Fans to suck in OUTSIDE air.  It was winter (< 32 dF) and the interior was warm.  He said it was easy to locate the incoming cold air.  He made several attempts at foaming the suspected openings and finally got it reasonably air tight.  He also found that there was air coming in from the cable and wire opening in the FRB.  That sounds like a good job for this winter.  My complaint is that there is not enough heating and cooling for the front cockpit.  He found a source of Black expanding foam at HD and matched it up.  Will have to do some brushing and cleaning to get rid of all the road grime.....compressed air will be my friend.

That's it.  I am now more confident that I found the source of the black snowflakes.....but how they got there....I don't know.  Time will tell.  There is no dangling sheets or strips of it under the Genny cavity now....so we will proceed as if things are fixed....or at least we have eliminated the bulk of the contamination. 

Thanks for the responses.... 

[Bob Nodine]

Just a comment about your comment about two air conditioners not being sufficient for a 41 foot motorhome. We have two of the newer Penguin High Output air conditioners and they do a nice job of cooling the coach. When the weather is hot we don't fool around and start the driving day with the fan on high on both units and the temp setpoint for the front unit at 72 and the rear at 69. The generator is started as soon as the coach comes out of the garage. While driving we also run the dash system on Max. The coach always stays comfortable and on our trip last week to Kentucky Horse Park the outside temp was in the high 90's in the afternoon all four days. Once parked we cover the front windshield if the coach direction has the sun shinning on the windshield in the afternoon. At night we always put the front unit on auto for the fan and move the temp setting to about 78 and the rear unit on either medium or high fan speed with the temp at 69. That keeps the front of the coach comfortable for watching television and the fan is not running creating background noise. We leave things that way all night because we like to sleep with the white noise from the air conditioner fan. We also like the bedroom cool and prefer using a blanket to sleep as we like the weight on our bodies.

[Tom Cherry]

4 hours ago, Bob Nodine said:

Just a comment about your comment about two air conditioners not being sufficient for a 41 foot motorhome. We have two of the newer Penguin High Output air conditioners and they do a nice job of cooling the coach. When the weather is hot we don't fool around and start the driving day with the fan on high on both units and the temp setpoint for the front unit at 72 and the rear at 69. The generator is started as soon as the coach comes out of the garage. While driving we also run the dash system on Max. The coach always stays comfortable and on our trip last week to Kentucky Horse Park the outside temp was in the high 90's in the afternoon all four days. Once parked we cover the front windshield if the coach direction has the sun shinning on the windshield in the afternoon. At night we always put the front unit on auto for the fan and move the temp setting to about 78 and the rear unit on either medium or high fan speed with the temp at 69. That keeps the front of the coach comfortable for watching television and the fan is not running creating background noise. We leave things that way all night because we like to sleep with the white noise from the air conditioner fan. We also like the bedroom cool and prefer using a blanket to sleep as we like the weight on our bodies.

Thanks.....the New Penguins will probably be our next "upgrade"....after the old ones die.  Totally agree with your concept.  Once you get behind....it is hard to catch up.  I need to revert back to the foil interior coverings.  I might even think about a front windshield cover.  The glass cabin is a virtual Heat or Cold SINK.  All you can do to cut down on that load helps.  

[johncvandoren@gmail.com]

Where do they sell that closed-cell foam? Mine has both black or silver colored versions, depending on location.

[gofastnow]

On 7/29/2020 at 1:35 PM, johncvandoren@gmail.com said:

Where do they sell that closed-cell foam? Mine has both black or silver colored versions, depending on location.

McMaster Carr is a good start