Weird fan fault Peugeot Expert. Fixed by removing fuse!?!?

[Discus]

This has me stumped! Please read on for a brain teaser.

I have a 2003 Expert HDI with air-con which I bought six years ago. The heater fan has always run - even in the off position. The slider worked to increase the speed & the air-con works fine.

Last week I had a new windscreen fitted. Afterwards, the fan was very noisy - making a 'thrumming' noise as through there was a piece of cardboard hitting the blades. I assumed something dropped into the fan & was stuck.

At the weekend, I had to do an 8 hour journey. After 30 mins I had to stop, as the noise was giving me a headache. I looked at the handbook & with the engine running, tried taking out all of the fuses related to the fan in the dashboard fuse board. None stopped the fan running.

I then tried taking out every fuse in turn, with the same result. There was no info on relays, so I tried removing each of 3, no change.

Getting desperate, I went under the bonnet & removed the 20A fuse. RESULT! The thrumming noise stopped, the fan worked fine, although perhaps a little slow. It now switches off with the slider in the off position, and the air-con works! Everything else is working fine.

I have a vague idea that somehow the relay has bypassed & maybe the wiring will be overloaded, but I have done 600 miles with no blown fuses or fire!

Any ideas gratefully received!

 

[telectrix]

i'd suspect the fan speed controller. had similar in a renault .fan ran at full speed all the time. not sure about the expert, but usually this is located under the dash fascia, passenger side.

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[Discus]

Thanks Telectrix, I used to think that, but why is it now working almost perfectly after I take out the fuse?

 

[PEG]

Hi dude,which fuse is shown as feeding the blower,and what is the fuse you have removed,shown supplying? Also,check on a model-specific forum,if that heater unit has electric servo control of any functions,there may be more than one fault occurring. Cushti boc

 

[davesparks]

You're thinking like an electrician here!

A 2 speed vehicle fan will almost certainly have 2 fuses, 1 for high speed and 1 for low speed. It's not like installations where the whole unit would be fed by one fuse!

It's most likely that the speed control switch has failed closed on the high speed setting/terminals so the fan will always have it's high speed supply on whatever position the switch is in.