What causes my RV to smell like my holding tanks when the A/C is running?

Your RV’s air conditioner unit works by drawing in the hot air from inside your RV, expelling heat outside of the RV, and then pushing the cool air back into your RV through the air vents. RV air conditioners are located on the roof of your RV, obviously, which also happens to be where your RV’s holding tank vent pipes are located.

Our guess is that your air conditioner is pulling smelly air up through the vent pipe, into the unit, and out into your RV’s interior. This wouldn’t normally be an issue when the RV is outside in (somewhat) windy (to some degree) weather, but if the RV is being stored inside or in a wind-protected area, the unit is most certainly siphoning off sewage gases.

If your RV’s sewage system vent pipe doesn’t have a cap on it, consider adding one to help minimize the siphoning situation. The Camco Cyclone is an excellent wind-powered pipe cap that will draw tank odors away from your RV. It also is a bit better “contained” than just a standard cap and may deter some siphoning of sewage gases in low-wind situations.

Jim & Debbie Tome, Owners

Hi, we're Jim and Debbie Tome and we're the owners of Kleen Tank LLC, the nationally-recognized and largest professional network of RV tank cleaning service provider.

We've been RVers like you since 2004 and have traveled all over the U.S. in our Airstream travel trailer. We started the business about twelve years ago and have cleaned tens of thousands holding tanks in thousands of RVs. From tiny weekend travel trailers to monstrous fifth wheels to luxurious motorhomes, we've seen just about every situation there is with RV holding tanks and waste systems.

We hope you enjoy our question-and-answer articles; we try to post at least a couple per week and we've got a great library of them to cover just about every problem.

And if you like these short question-and-answer posts, be sure to check out our main Kleen Tank website which contains years of longer-format articles that go more in-depth on many topics. Enjoy!

Keep in mind that we may receive commissions when you click our links and make purchases. However, this does not impact our reviews and comparisons. We try our best to keep things fair and balanced, in order to help you make the best choice for yourself and your RV.