Help! My RV air conditioner sounds like a ‘dying cow’

Dear Dave, 
My RV’s side air conditioner (I think) makes a noise in the wind like a dying cow. I can’t find where it comes in so I can block it. How can I make it stop, please? —Terry, 2015 Riverside Retro 177

Dear Terry,
From the photo you sent, it looks like you are referring to an in-the-wall-type air conditioner, which would be similar to a window air in a residential setting. I have had some experience with these; however, it’s been about 40 or more years since I had a rental house with one or more of these units.

I also assume you are getting the “dying cow” noise while parked and the wind hits the side of the unit while you are inside; otherwise, you would not hear it. So the wind could be coming from any direction hitting something and making the noise.

The first thing I would do is identify all the components on the side of the rig that could be rattling in the wind such as the awning, door, windows, and the air conditioner.

When does the sound happen?

A few questions first. Does the sound happen when the air conditioner is not running? If yes, this eliminates the operation of the air conditioner and means that it is a wind leak. If it is only when the air conditioner is running, then it is something in the air conditioner that is rattling or a leak in the air chamber.

You should also be able to isolate the component using a mechanic’s stethoscope like this one available on Amazon.

Noise while air conditioner is running

If it is coming from the air conditioner while it is running, it could be the compressor is loose and vibrating. Or, it could be weak and running under load or high amp draw and making a throaty sound. You should be able to identify this with the stethoscope. That would typically mean a new unit is needed, unless your air conditioner can be recharged.

Noise when air conditioner is not running

If it is coming through the air conditioner when it is not running, then it must be wind getting through the condenser coil on the outside or around the perimeter. You should be able to isolate that by taping a sheet of plastic over the entire opening on the sidewall to see if it stops. Do not run the air conditioner in this test; you’re just looking for wind leaks.

If it is coming from another source, you will need to isolate the source at either the windows, door, or even the awning which is protruding out and can catch a good wind. The slightest gap in sealant or even a window pane could allow air to penetrate and create the sound.

Isolating the actual spot of the noise will help determine what sealing procedure will work.

 You might also enjoy this from Dave 

My RV’s roof air conditioner drips inside when running. How can I fix it?

Dear Dave,
When running my air conditioner on hot days, it begins freezing up and drips water or “snow”. What is the cure for this little issue? Thank you. —Jeff, 2024 Coleman Lantern 274BH

Read Dave’s answer.

MORE FROM DAVE ON RV AIR CONDITIONERS

• What to use to power RV roof air conditioner when dry camping
• Why does air conditioner ‘cycle’ several times before staying on?
• When using generator, why does RV roof air conditioner drain house batteries?
• Can we test RV roof air conditioner with 110-volt outlet?

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

Read more from Dave here. 

HAVE A QUESTION FOR DAVE?

Send your inquiries to him using the form below.

##RVDT2608