Hi,

I was on a short trip today with AC on and fan speed on 'low'. Everything worked fine, until suddenly the blower speeded up and got significantly louder. I switched through all fan modes (low, medium, high) and found out that: low = medium, medium = medium, high = high.
I have heard about various HVAC issues like no function at all, or no function on low and medium ... but that low = medium, I haven't heard about that.

I know on newer cars there a several resistors that control the fan speed, but usually when one resistor fails the whole blower mode fails. Any idea to what my issue is related? Blower motor, control unit ... something else?

Thanks
Oliver

 

If it's on auto, this is normal behavior. The low will eventually slow down when the temperature differential becomes less.

 

Wow, I've got the car for 7 years now, but I never observed that behaviour. Maybe I was always on manual. Tried it again today and low was once again low.

 

Had the same behaviour today, but this time I turned manual mode on. But that didn't help. And it wasn't really hot today. Maybe something with the temperature sensor?

 

On really hot days low will blow hard till temperature comes down. Try it tonight or when things cool down and watch the difference.

 

It was about 20°C (=68°F) yesterday, so really no reason to stress the blower. I also noticed that I got wet feet a couple of times, that's probably coming from the drain of the evaporator.

 

Wet feet means AC drains plugged and blower full of condensate ... so spilling out on turns. Clear the drains or you will soon short out the darlington speed control and more.

 

Do you believe the condensate also could cause the odd blower behavior? Or are these issues independent of each other?

 

Not sure but clear the drains ASAP if I were you.

Pull back the carpet either side of the trans tunnel and locate the upper drain tube.
Remove the clear tube from the rubber and connect a long hose so that that end is outside of the car.
Attach an airline or aerosol and give it a few short blasts.
Remove the airline and let condensate drain. Reattach upper drain tube and replace carpeting. Repeat other side.

 

That's basically what came out on the drivers side. On the passenger side it was just a few drips. Let' see if that fixed something.