# Fan comes on for (apparently) no reason.



## FF35 (Jul 13, 2018)

No dog mode and climate controls are off. After finished driving, maybe 10 minutes, a fan can be heard on the outside of the car and it seems to be fast. It’s around the area of the windshield wiper.

When I open the door, you can tell the climate control isn’t what was on because the inside of the car is the same as the ambient temp.

The fan only stops when I open the door. It will run for about 10-20 minutes. Ambient temp can be hot or cold and the driving can be 5 minutes or an hour. I can’t figure out why it happens.

Anyone had this problem before?


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## PiperPaul (Oct 31, 2018)

FF35 said:


> No dog mode and climate controls are off. After finished driving, maybe 10 minutes, a fan can be heard on the outside of the car and it seems to be fast. It's around the area of the windshield wiper.
> 
> When I open the door, you can tell the climate control isn't what was on because the inside of the car is the same as the ambient temp.
> 
> ...


Yup; me too. 
My Mobile Rep suggested I had it in dog mode but have never used it. I suspect it has something to do with battery management, but only a guess.


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## FF35 (Jul 13, 2018)

PiperPaul said:


> Yup; me too.
> My Mobile Rep suggested I had it in dog mode but have never used it. I suspect it has something to do with battery management, but only a guess.


What's even stranger is that disconnecting the 12V battery doesn't stop the fan.


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## JasonF (Oct 26, 2018)

FF35 said:


> The fan only stops when I open the door. It will run for about 10-20 minutes. Ambient temp can be hot or cold and the driving can be 5 minutes or an hour. I can't figure out why it happens.


That's the cabin fan running with the outside air door open (which is why it sounds different) to try and dry out the evaporator. It's supposed to prevent wet dog wearing dirty socks smell at A/C startup.


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## FF35 (Jul 13, 2018)

JasonF said:


> That's the cabin fan running with the outside air door open (which is why it sounds different) to try and dry out the evaporator. It's supposed to prevent wet dog wearing dirty socks smell at A/C startup.


Even if you haven't used the A/C or defrost in a week, especially when the humidity is 20%?
Also, strange the Tesla tech didn't know that.


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## JasonF (Oct 26, 2018)

FF35 said:


> Even if you haven't used the A/C or defrost in a week, especially when the humidity is 20%?
> Also, strange the Tesla tech didn't know that.


I don't think the logic behind it can tell what you ran while driving, it only knows when you get out of the car after driving it.

All the normal fans/sounds while the car is parked that I know about:

- Air rushing/Fan noise running "inside a box" - cabin ventillation fan
- Loud whirring electric fans - front radiator cooling fans
- Metallic whirring noise that ramps up - A/C compressor
- Quiet "aquarium pump" whirring noise - coolant pump
- Quiet trickling water sound - circulating coolant
- Distant pulsed metallic hissing - A/C refrigerant pressure balancing
- Loud double "heavy desktop stapler" clunk - Contactors opening/closing
- Soft metallic repeating clunk - chilled refigerant from A/C contracting internal battery parts
- Metal pan clunk during supercharging - battery heating deforming the panel on its top
- Steady quiet low pitched noise from the motors while parked - motor poles being charged to scavenge heat for the battery
- "Ticking Bomb" sound from the left rear - charge port lock repeatedly locking/unlocking


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