355 the cabin blower turns on by itself at maximum speed when engine is running

Hi Guys,

I had the great pleasure of driving my wonderful f355 today.
To my surprise, after starting the engine, the cabin fan turned on at stayed at highest speed. Nothing changes when adjusting the potentiometer. I stopped, turned off the engine and after a while I started again and the cabin airflow turned off and I could operate it normally by adjusting the potentiometer. Unfortunately when I was returning home it turned on again at the highest speed and did not respond to the potentiometer adjustment. Please help, where should I start?

Thanks
K

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I had the same problem and it's most probably the power transistor part 63307200

 

Thanks. Where it is located in the car?

 

It's located at the red arrow in the evaporator left side.
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thank you for the information. Where can I get to this? Need to remove the dashboard?

 

From the left side in the luggage compartment, pretty much self explanatory in the pic above.

 

You need to remove the forward luggage compartment liner. It's in the frunk.

Also known as the fan speed regulator, power unit, hedgehog (on 360/430), etc...

No longer available or vary rare. If you look a parts websites, they indicate this by quoting ridiculous prices e.g. $3,153.49 at Eurospares. Best bet is to repair it.

https://www.ferrarichat.com/forum/posts/148363788/

 

Thanks guys, it took me 9 minutes.
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It's easier to find under fiat part number
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Now you can start testing the unit according to what Qavion showed in an earlier thread.

https://www.ferrarichat.com/forum/posts/148363788/

 

I'm here
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I have no idea how to pull it out. I tried to pull using pliers for the contacts but unfortunately it does not move...

 

Pull what out? it's already pulled out above right?

 

It's need to be removed for fixing?

 

Just test it first, otherwise buy a new one, they are hard to find though...

 

Don't force it. It's soldered in. See here:

https://www.ferrarichat.com/forum/posts/144926634/

 

So there's a chance it's working fine and that's not the cause of the problem??

 

The HVAC ECU is sending a control signal, so it's possible that that is faulty. @m.stojanovic has some tips on faultfinding.

One of the repair shops, technozen-electronics.co.uk, has this warning:

 

That's a nice watch and lexus brochure! I would definitely bench test that before ripping it apart. If it fails, then repairing it may be the only solution.

 

I have not replaced the motor, might do that when i have repaired everything else in the HVAC system.

You know where i can find a new motor or OEM part?

 

It's not available new (I don't think it ever was). Here's a message thread on the motor (There may be others).

https://www.ferrarichat.com/forum/posts/148604025/

 

Thanks, seems like the whole evaporator unit needs to be removed....

 

guys, where HVAC ECU is located? I understand that there is a high chance that it is actually damaged?

 

consedering rx500h as time to buy suv finally.

 

Passenger side, under the "frunk" cover, between the shock and firewall. It's in a "box" like unit, not sure if you can make this out but it's the only photo I have:

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