Why is it snowing Styrofoam beads and debris from my RV’s A/C vents?

Dear Dave, 
I have debris coming out of two A/C vents in my RV: one in the kitchen over the island, and one in the bedroom over the foot of bed. Here’s a picture of the debris I collected. It looks like leaves mixed in with Styrofoam. Thank you. —Ilene, 2015 Heartland North Trail 23RBS travel trailer

Dear Ilene,
Your Heartland RV has a single 13,500 Btu roof air conditioner that has ducted ceiling vents that distribute the air from the unit. That setup is much more efficient than the units that blow air from the unit itself. The ductwork for those vents is either routed in the block foam insulation of the roof, or a fabricated ductwork made of thin foam with a wrap.

It is not unusual to see some “snow” in the initial operation for a few times, as the routing and installation will have some beads still in the ductwork. It gets blown out and even additional beads break off and flow to the vents.

However, since your unit is more than 8 years old, there is something going on in either the ductwork or the air conditioner itself. Plus, the other debris looks like leaves and small branches, so I would guess that you had or still have a visitor living in your upstairs apartment! Mice and squirrels love insulation in the cold weather as it makes a great nest. They can get into the unit or the ductwork in a variety of ways.

Here is a photo of a local unit that had a similar situation last year. The owner took off the cover and plugged the unit into shoreline power. When he turn the air conditioner on, it snowed inside the unit like it was Christmas Day! A squirrel had chewed its way through the vent of the cover, chewed through the plastic cover of the roof air conditioner, and burrowed inside the unit gnawing at the foam all winter. When he took off the evaporator shroud, the entire foam insulation was in a hundred pieces.

First thing to do to check RV’s A/C vents

The first thing I would suggest is to remove the inside cover of the return air on the ceiling and see if the ductwork looks like it has been chewed up. You might need to get an endoscope and fish it through the ductwork to the vents. They are very inexpensive and you can get one on Amazon here.

If the ductwork looks to be good, you will need to remove the cover of the air conditioner and possibly the metal evaporator coil cover. My guess is you have or had a squirrel that brought in additional bedding from trees and is getting free rent! It could also be mice, but the debris field seems a little large for that.

Be careful, as squirrels can be rather dangerous when trapped in a small area. If it is still in there, you want to stay away as it thrashes around. Note: You might want to set up a camera as this could be worth $20,000 on Funniest Home Videos!

The best way to keep squirrels out is to completely cover the roof air conditioner with a canvas cover and use a squirrel deterrent. Most do not like any kind of mint; however, there are several natural deterrents found in home improvement stores.

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