Hello, my Ford Fiesta blower works as expected on each speed setting, but only for a few minutes. After a few minutes the amount of air coming out slowly subsides until almost no air is coming out, even though you can hear the fan speed noise the same as when air was being blown properly. If the system is turned Off for 30 or so minutes, it will work normally for a few minutes and then slowly subside again and repeat the same issue. This issue happens regardless of whether actual A/C is being used or not. 

Thanks!

Have you checked the other vents to see if air is being diverted to feet or windscreen? 

If the fan is still running at the same speed, the air must be going somewhere.

Tom,

I have checked the other vents, and the same scenario happens to those as well. The air slowly subsides from all of the vents. I agree with you in terms of logic that the air must be going somewhere, which is why this has been very confusing as to why the air slowly decreases through time even though the sound persists.

I wonder if there's a different noise in the same area causing confusion?

Sounds like motor or resistor is overheating to me.  Then works fine again once cooled.

That's the best suggestion I can offer right now unfortunately.

Okay thanks. Do you have any advice on how to check those for overheating?

16 hours ago, boebyu said:

Okay thanks. Do you have any advice on how to check those for overheating?

If you can get any visual access to confirm the blower motor is stopping that would be good.

If not, I'd probably just try changing the resistor as it's fairly cheap and easy to replace.

 

On 8/9/2023 at 5:14 PM, TomsFocus said:

Sounds like motor or resistor is overheating to me

If it was the resistor it wouldn't be happening on the maximum blower setting as all sections would be switched out of circuit so no heat would be generated.