Outside Smoke is coming inside thru the AC!!!

[VeggieBullet]

Hi guys.
Is this normal with the Rv AC? Why is the AC always bringing the outside smells into the trailer?
When someone is making a fire somewhere it is just terrible inside, not considering the toxicity factor..
Does everyone else have the same issue?
The Ac unit is a Low Profile Penguin /Duoterm by Dometic
Any inputs about how to fix this will be great.

[Aage]

It is unusual: it is my belief that the AC units do not pump outside air in.

There is a fan that takes inside (cabin) air in, chills it, then blows it out again. The fan shaft also drives a fan blade on the out side that serves to blow outside air over the cooling fins of the plumbing of the AC unit.

No air is taken into the cabin of the trailer, from what I have learned about AC units.

[TBRich]

That's my understanding as well. When we've had outside campfire smoke odors inside, it's been through the vents or windows, especially if the Fantastic Vent is powered up and blowing outwards...(bringing in air through other openings)...

[slowmover]

May be a good idea to R&R the A/C unit. Be sure there are no low spots, etc, where air could be drawn in. An extra-thick gasket is available from RV supply houses. I've done this on both SS trailers as I assumed (correctly) that age had deteriorated them past the point of usefulness.

Also a good time to clean condenser and evaporator coils.

[garry]

Sounds more like an open bath vent, bad gasket or air leak around the widoows.

[arcamedies]

I was told, nope it can't happen but when the a/c took a dump and the new Penguin was installed the black tank smell I would get with the wind blowing from the rear dissappeared instantly. Flush toidy and instant smell from a/c vent blown in face, not pleasant. Dometic even notes and improved seal with the new units preventing outside odors being sucked into the low presssure side and distributed into your airstream.

[Protagonist]

There is one way it could happen. Looking at the Duo-Therm AC Service Manual that I downloaded from http://bryantrv.com/docs2/docs/acservice.pdf, the return air plenum surrounds the cold air duct. The return air plenum is insulated where it penetrates the roof, and this insulation is supposed to form an airtight seal. If the insulation around the return air plenum is not installed properly (not forming an airtight seal), it is possible for outside air to leak in and then be drawn into and distributed by the AC fan.

[slowmover]

Gasket. The pressure differential is the culprit.

[Protagonist]

Originally Posted by REDNAX

Gasket. The pressure differential is the culprit.

Yeah. The manual doesn't call it a gasket, but that's what it is.

[jm2]

VeggieBullet, in addition to Protagonist's suggestion,

there is about nine feet of 1-1/4" square foam tape located in between the top of the airconditioner chassis and the underside of the Penguin shroud. that foam tape separates the "inside air" blower wheel plenum from the "outside air" blower wheel plenum.

here's some drawings - Replacement Shroud Penguin Low Profile Rooftop RV air conditioners 3308046.006

when I replaced our Penguin shroud, the directions said to apply the new foam tape to the inside of the shroud (as in Figure 1). judging by the amount of compression to the old foam tape, you could easily see that the tape was mislocated in one area.

I couldn't imagine being able to locate it properly or completely like that, so I installed it to the top of the chassis, instead (as in Figure 2). it works fine there!

I'd pull the shroud to make sure that foam tape is properly in place....

best,

[slowmover]

I used a couple of rolls of 361-11 NASHUA Waterproofing Repair Tape (butyl-backed aluminum foil) when installing the 15K RVP A/C unit last March. From the interior of the A/C opening to a fair distance outside.

Also used some outside on an exterior wall. Does what it claims and then some. Heavy downpours have not fazed it.

.

[VeggieBullet]

Hi Guys
Sorry for the delay on getting back to the thread.
wow...that's a lot of info, need some time to digest...

[VeggieBullet]

please excuse our ignorance in the subject and therefore the following confusion.
Are we talking here about :
1) the gasket that is used when installing the AC? Solution: Remove the AC and replace the gasket and cleaning the condenser and the coils.
b) Is there a gasket for the Shroud that has to be replaced and that it doesn't require the removal of the all unit?

[slowmover]

Yes, to No. 1

No separate gasket for shroud (some NVH foam in a few places underneath).

The unit is heavy, but really one is just propping it up and sliding it onto a tarp or something while the opening is cleaned/prepped and gasket (cushion) is replaced.

I used the tape as the surface the gasket sits on (slightest build-up from roof) but started (as did Silver Streak) by sealing the roof opening (smaller than the A/C opening that will go over it). I continued this into the interior going just slightly farther than did the factory. Same for roof.

Drop the A/C in place (center from interior) and evenly "clamp down" the unit per instructions (X-pattern; gradually).

.