Hi All,

I bought an approved used Mazda CX-5 in March 2024 with around 34,000 miles on the clock from an official dealer in London. The car was manufactured in 2020. As we head into summer (and perhaps the demands on the air conditioning unit have increased), I have noticed that there is a whining sound coming from the air conditioning unit behind the dashboard. The sound does not become apparently immediately after the engine is started up, but perhaps around 10-15 minutes after this. In addition the sound is intermittent. At first I did not know what was causing the sound, but when I switched the air conditioning unit off the sound disappeared immediately and the cabin became quiet. I've tried this a few times and the sound consistently disappears immediately, so I am pretty sure the noise is coming from the air conditioning system.

Does anyone have any advice on what I should do?

Many thanks in advance,

Geoff

 

Welcome to the forum

Is the sound only with the AC on or does it also happen when you use the heater? What blower motor setting/speed are you using when you hear the sound?

 

Hi,

Thanks for your response. I will check all these aspects and let you know tomorrow.

Kind regards,

Geoff

 

A video of the noise be a huge help as well.

 

A helpful FYI for future reference:
A noise as described it would be better to post the answer to what I asked before posting a generic video. But in the case of interior parts operational noises, you must ask specific question and also instruct where and how a video regarding an unexplained noise must be taken. Otherwise, background and other normal operation in a video can all sound disturbing at times and harder to separate normal noises from questionable. ones.

 

Hi,

Regarding the sound, I tried switching off the A/C and left the heater on. The whining sound remained apparent, but was not too loud. When I manually increased the fan speed, it was difficult to detect the whining sound as the noise from the fan suppressed the quieter whining sound. I hope this helps, but let me know if there is any other information that you need.

Kind regards,

Geoff

 

Could be as simple as a leaf stuck.

 

+1 Fantastic knowledgeable free advice. I had a hum in my CX-5 that was fan speed specific. It sounded electrical but was just a vibrating leaf stuck. It may not be the issue but it only takes a few minutes to check and costs nothing.

 

Its is easy to drop the fan out and inspect the blower case.
But in my experience larger parts getting past the intake cowling vent sound more like a bicycle with a playing card attached to the frame and hitting the spokes then a whine.

The test procedure I suggested is pointing more (*a GUESS) the motor itself is starting to fail. All electrical motors when the armature has a problem will produce an ever-increasing high pitch whine.

A video taken with engine off but power acc. on at the blower motor area and various fan speeds at this point may be a little more helpful?


* As a hard fast personal rule I seldom ever GUESS causes on any forum because there is usually not enough information and verified facts to formulate the exact cause of a problem.