S9 ResMed making howling noise...never used to

I noticed that mine cpap machine is now making a howling noise. Sounds as if wind blowing through the window at night.

What could be causing this? I've replaced the grey dust filter on the outside of the machine.

I have knocked it off the night table a couple of times. Hope I didn't damage anything inside.

Has anyone else come across this problem?

If it is still under warranty (less than 2 years old) I would contact your DME and see if they could swap it out for you. I would probably omit the portion of your story where you mention knocking it off the table during the discussion. This should be a simple process.

Sell it to STL Mark for resale and buy from him an S9 Autoset

What causes the howling? Can I fix it? My machine is over 2 years old.

Why did it start doing this?

A slight whistling noise has been reported in the S9 upon exhale. No one has mentioned a howling noise ... especially after 2 years.

Well I guess it could be a whistling noise.

Is that common for the machine to get that after years of use?

jarablue wrote: Is that common for the machine to get that after years of use?

Not normally.
The noise on exhale usually is there from the beginning and the sound can be diminished by changing the force of exhal and the noise is only on exhale.

So is your noise constant or come and go with inhale and exhale?
Have you checked the seals inside the humidifier and tank connection to make sure those are like they are supposed to be?

I don't use the humidifier, the hose is plugged straight into the main case. It's only on inhale do I notice the whistling/howling. If I take off my mask and let the air blow you can hear it constantly.

I don't know what else to check.

Sounds like there is a problem with the fan motor or something. I don't do machine repair stuff.
It's not normal for a normally quiet machine to suddenly become loud and producing sounds it never made.
Since you hear the noise when just letting the machine run...something is going on but I have no idea what it might be.
It could be signs that the machine is starting to have some bearing or whatever wear out.
Probably needs to be serviced.
Do you have insurance? Even if out of warranty insurance will normally either pay to repair or replace an ailing machine.
If you don't have insurance...well you are stuck between a rock and a hard place.

I would be contacting the DME who supplied it (minus the knocking off the table thing which very well could have damaged it) and seeing what they can do. If you have insurance check to see what their policy is regarding machines that need repair.
Sometimes DMEs will supplier loaner machines while ailing machines are sent to see why they are ailing.

jarablue wrote:I've replaced the grey dust filter on the outside of the machine.

Not trying to sidetrack this discussion.

But, I was not aware that any S9 had a grey dust filter.
I thought that all of the S9 filters were white (either "standard" or "hypo-allergenic").

StuUnderPressure wrote: But, I was not aware that any S9 had a grey dust filter.
I thought that all of the S9 filters were white (either "standard" or "hypo-allergenic").

I suspect it was "grey" because it was originally "white" and hadn't been changed in a while.
Mine turns a nice even grey color when I let it go a bit too long.