Heating fan

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daviemck2006
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Heating fan

Post by daviemck2006 »

As my heating fan has it's control module removed for repair and the wiring bypassed until it's fixed properly you would think it would go at a steady full speed all the time. However is doesn't. The speed is variable every time I start the car. Would this be an indication that the power supply through the ignition is not the best? Could I need to do the relay mod? If so would i get a relay, cut the thick red wire which goes into the brown plug and use this as coming from the ignition to trip the relay. Take a live direct from the battery through a fuse to the relay then from the relay to the brown plug. Can i join the earth from the relay to the black wire or or find another earth? Wiring even the simplest things is a black art for me so any pointers are appreciated. I'm also assuming that relays have 4 pins and are marked which pin goes where.

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Re: Heating fan

Post by CitroJim »

Yes, you need to do the relay mod Davie...

There are plenty of posts on here detailing how to do it properly.. A search should reveal ;)
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Re: Heating fan

Post by white exec »

daviemck2006 wrote:. . . The speed is variable every time I start the car . . .
Hi Davie,

What you describe - fan speed varying when starting - is not unusual. When IGN is switched on, several bits of electrical kit will start to operate (even more so if yours is diesel), and the battery voltage will drop. When you crank the engine, it will drop even further, and the heater fan speed will slow, along with interior lights etc etc visibly dimming.

When the engine fires up, a large alternator output will kick in, and supply voltage will rise appreciably. This will result in the fan speed increasing noticeably.

It's this varying system voltage that is responsible for the fan speed varying so much on start-up.
Chris
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Re: Heating fan

Post by CitroJim »

Davie, I tested your blower module today in my Activa and it works perfectly so your fault lies elseware...

I'll pop the module in the post on Monday complete with that funny foreign banknote you enclosed... :lol:

The other module I'll sort out in due course and return that too..

Chris, you raise a good point... What is the speed variance on the fan? Basically, in pursuit of another test I did today, once the engine is running and the load is light on the alternator the voltage should remain constant so if the fan varies in speed with the engine running and you know the alternator and battery is good then it's likely the relay mod would be a good idea.

Does the fan speed vary if you wobble and jiggle the ignition key?
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Re: Heating fan

Post by myglaren »

Speaking of funny looking banknotes- these are wierd.
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Re: Heating fan

Post by daviemck2006 »

With the engine running the fan varies in speed from full blast it slows down, eventually just going and no more. Then when I shut the engine off then start it again it always starts up blowing at a high speed before slowing down again

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Re: Heating fan

Post by CitroJim »

myglaren wrote:Speaking of funny looking banknotes- these are wierd.
They are indeed but good to look at :) I enjoyed that link...

The one Davie sent me was a Scottish Tenner... I was amazed at how much different they look from English Tenners...

the most worrying part was the portrait of Nicola Sturgeon in place of the Queen on it... I'm wondering now if it is legal tender south of the border!

Anyway, it's now on its way back home ;)
Davie wrote:With the engine running the fan varies in speed from full blast it slows down, eventually just going and no more. Then when I shut the engine off then start it again it always starts up blowing at a high speed before slowing down again
That sounds like the switch Davie but if you have a voltmeter please check the volts across it... If they don't change but the motor speed does then the motor is duff...

Else that, try running the motor direct from the battery - bypassing all the wiring...

If you can do those tests before Monday and prove the motor is duff I can send you one along with the blower module...

I have a couple of spares here...
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Re: Heating fan

Post by daviemck2006 »

I did test that Jim. It's showing a steady 14.4 volts across the red and black on the brown plug coming out of the wiring look. When I stripped the module off the motor there was a large amount of dust came out. Could this be an indication of the motor being fuxxxd?

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Re: Heating fan

Post by CitroJim »

Dust is not a problem normally Davie... They do get mucky in service naturally...

If you are content that the volts remain constant but the speed changes then I'll dig you out a replacement fan motor assembly and despatch it to you on Monday...
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Re: Heating fan

Post by daviemck2006 »

Hold off posting the module back Jim, I won't have a chance to investigate tomorrow, but on Monday I will remove the motor again and connect it directly to the battery just to see what happens. I am going to buy a relay and wiring tomorrow while I have to go to Aberdeen, in the activa of course. 100 miles of windy roads [emoji4]

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Re: Heating fan

Post by CitroJim »

OK, I'll hold Davie but please be aware the next time I can get to the PO after Monday will be Friday... Is that OK?
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Re: Heating fan

Post by daviemck2006 »

Yes, it's no problem. It's too cold, too dark and too wet and my hands too sore after fixing a wiper linkage on the Leon for me to look tonight now. Leons are funny beasts, totally separate motors and linkages for each side. It's a wonder they don't tie their wipers in knots. The wipers park upright at each side of the screen. Funny Spanish ideas. The only good things that the Spanish make are tapas [emoji23]

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Re: Heating fan

Post by CitroJim »

No worries Dave, I know what you mean about the cold and the Leon wipers really are quite bizarre. Wonder what the reason is?
daviemck2006 wrote:The only good things that the Spanish make are tapas [emoji23]
:lol:

Thev're produced some very good bicycle racers in the past Davie and do an excellent bicycle race each year, the Vuelta ;)
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Re: Heating fan

Post by elma »

daviemck2006 wrote:Yes, it's no problem. It's too cold, too dark and too wet and my hands too sore after fixing a wiper linkage on the Leon for me to look tonight now. Leons are funny beasts, totally separate motors and linkages for each side. It's a wonder they don't tie their wipers in knots. The wipers park upright at each side of the screen. Funny Spanish ideas. The only good things that the Spanish make are tapas [emoji23]
Dads 308 is like that but I don't know if there are separate motors and linkages.
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Re: Heating fan

Post by RichardW »

Most are going that way now (although Cit generally still park at the bottom) - the C4 Picasso does, as does the X7 - they also have an ECU in each motor, if this goes belly up then a very expensive repair beckons.... (motors £250 each at the last look!). Interestingly (if you're sad like me) you can see that they are individually driven as when they re-park from the service position, they do it one at a time, not together.
Richard W
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