2001 F360 Modena Bower Motor Stuck On

Hi - the blower motor on my F360 is stuck in the full blast on mode whenever the battery is connected. Nothing turns it off other than disconnecting the battery. Anyone run across this?

 

That's going to be a hard one to pin down.

Control Panel?
ECU?
Fan Controller ("hedgehog")


In the meantime, there is a green 30 amp fuse on the side of the evaporator (in the cabin) which will kill the fan (only) if you want your battery not to go flat.

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I don't know if it's possible to isolate the issue by pulling the plug on the control panel. When I do that on my F355 I vaguely recall that fan still runs (perhaps at a default speed).

I think fan controllers are no longer available, but they can be repaired by specialists.

 

The fan controller has two connectors. If you disconnect the 2 pin connector, that will also shut down the blower fan.

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Rethink:

The blower fan uses live battery power. The fan seems to be getting a direct earth/ground from somewhere (to complete the circuit). This can either come from a short in the fan wiring or from the fan controller. The circuits in the fan controller seem to be powered by key power (via the orange wire), so perhaps should not be operating with the key turned off.

Does this mean the fan controller has a short?

If you disconnect the 5 pin plug instead of the 2 pin plug on the fan (speed) controller, does the fan still run at full speed when you turn on the battery?

 

A history would have been helpful....

https://www.ferrarichat.com/forum/posts/147957919/

Has your fan speed controller blown up again?

Perhaps your fan is drawing too much current?

 

I replaced the power transistors in the unit shown in the diagram a couple years ago when the fan failed in the off condition and it fixed it until now. Tried to get a replacement unit but they were not available

 

Thanks. That at least allows me to keep the battery connected.

 

https://www.technozen-electronics.co.uk/mg-zs-rover-45-climate-control-repairs/

 

It failed in the off condition a while back. I couldn’t find a replacement controller so I opened the unit and replaced the failed power transistors. That worked until now, when its failed in the open condition. I have not checked the current draw on the motor as I assumed the electronics were protected by the fuse. Is that a known issue - excessive current draw causing a failure in the full on mode?

 

I'm really not sure of the internal circuitry of the controller. I imagine that the power transistors normally limit the current going to the fan (hopefully before the fuse blows).

I'm no expert in electronics. Can an overheated power transistor go short circuit, providing a current path for the fan motor?

Also, I don't know if the live battery power is used in the transistor bias circuits or if the control is all done with key power. Maybe you could try pulling the 5 pin plug on the controller, removing the control signal from the ECU just to see what happens (even if this might not help with diagnosis).

 

This is interesting as the motor runs at full speed anytime the battery is connected regardless of key position.

 

I was just reading up on power transistors and I believe they can fail either open or closed. Last time they failed open. I’ll run through the diagnostics again.

 

Of course, there might be other components in the controller causing this issue. Did you take any photos of the internals last time?

 

To update. I installed a small toggle switch under the dash on the power wire to the motor (green) fuse so I can operate the car while I order power translators (again) to replace them in the regulator. I’ll check the current this time to see if that’s what’s causing them to fail.

 

Just to update. Tester power transistors and they were bad again. Replaced them, which only took an hour this time, and everything works fine. What I’ve learned is failure of the system off (1st time a few years ago) and the more recent failure with the fan on full blast were both caused by the transistors failing. Root cause may still be the current draw out of the fan which I still need to check. I left the toggle switch on the input power in place so I could leave the system off and still drive the car while I figure out this last item. Appreciate all the assistance through the forum.

 

@mxbennett Thanks for the update!

 

Any further updates? I believe I am having the same issue. Did you ultimately find the underlying issue?