2018 Mazda CX-9 air speed fluctuating?

[panthermike]

It was real cold out today and I put the defrost on max actually defrost with feet blend setting. Immediately noticed it sounds as though it's blowing and then slows down and then goes back up for a while not a dramatic increase or decrease but there.

My first thought was to check the cabin filter which I will but not sure if that would cause a fluctuation doesn't seem like it to me. Any thoughts?

 

[Greasymechtech]

Battery voltage and alternator management

Or, the fan is burning out

 

[Jetronic]

yes monitor alternator voltage, it could go up or down by load or by engine rpm

 

[Reggaemon]

Automatic temperature control variation. Mazda fan speed bounces around a little until it decides what it wants to do.

 

[panthermike]

Automatic temperature control variation. Mazda fan speed bounces around a little until it decides what it wants to do.

So for Mazda this would be considered normal? I will say after driving about 5 plus minutes it's still doing it only on the highest two fan speeds.

 

[Reggaemon]

So for Mazda this would be considered normal? I will say after driving about 5 plus minutes it's still doing it only on the highest two fan speeds.

Does the fan speed display show the changes in fan speed..that is the number of bars going up or down. When I 'm in auto temp it seems to respond slower than I think it should. If it's super cold it might be working properly.

 

[YZJB]

It’s normal. You’ll probably notice the fan speed increases during deceleration (like rolling up to a stop while braking gently) as they ramp up the alternator output during decel to save fuel. It’s very mild regenerative braking

 

[panthermike]

Does the fan speed display show the changes in fan speed..that is the number of bars going up or down. When I 'm in auto temp it seems to respond slower than I think it should. If it's super cold it might be working properly.

No actually it does not change on the screen as far as fan speed. Also this is and manual mode, I rarely use the auto feature.

 

[panthermike]

It’s normal. You’ll probably notice the fan speed increases during deceleration (like rolling up to a stop while braking gently) as they ramp up the alternator output during decel to save fuel. It’s very mild regenerative braking

I'm not sure I'll have to pay more attention to see if that's the case

 

[PimTac]

No actually it does not change on the screen as far as fan speed. Also this is and manual mode, I rarely use the auto feature.

Thanks for mentioning this. On my CX5 I also use the manual function as the fan speed seems to be overbearing on auto mode. When I push the defrost button the fan has a mind of its own and will speed up despite the fact that I have it on manual. I just readjust the speed back down and it’s stays there.

Mazda has some programming in their HVAC that I don’t understand.

 

[panthermike]

Thanks for mentioning this. On my CX5 I also use the manual function as the fan speed seems to be overbearing on auto mode. When I push the defrost button the fan has a mind of its own and will speed up despite the fact that I have it on manual. I just readjust the speed back down and it’s stays there.

Mazda has some programming in their HVAC that I don’t understand.

Hey thank you very much for commenting. Basically sounds exactly the way the CX-9 behaves. Pretty odd but glad to know that it's normal

 

[RedSpider]

Mine behaves the same way, as a matter of fact it did this just last night on the way home. Even with the fan on the lowest setting, when you hit the defrost button the fan gets possessed and pretty much does whatever it wants, and you have to readjust the speed down manually.