Whining noise on ResMed AirSense 10 / n30i

I have been using the ResMed AirSense 10 for almost 2 years. I changed from a full face mask to the n30i nasal pillows about 8 months ago. I love the pillows. Everything had been working fine ( whisper quite) until about 2 weeks ago when the system started whining. I have replaced the headgear, the pillow and the hose. It worked quietly for 1 night the started whining again. I am perplexed. Why can’t I get rid of the noise all of a sudden?

Most likely you can't get rid of the noise by replacing the mask with a new one is because the noise is coming from the machine itself. Whining noise is a common complaint when the motor starts to fail.
The noise is coming from the machine itself and you will likely have it happen no matter what mask you used.

Time to make plans to be getting a new machine or getting this machine fixed.

If..as you say...it's "almost" 2 years, it would be under warranty. Take it back to the dealer that sold you the machine. If it is not covered, acbio.com is a good place to check on repairs.

If your warranty is still in effect, waste NO time in getting it addressed.

This model is prone to a whining noise caused by the blower. You can contact ResMed to find the closest place to send your unit. The dealers tend not to repair these units, so you'll need a service center.