Fan replacement woes

frankgoldstar · 27th June 2017, 15:59

Dear All,

I have to say first that I have been wrong on my fan replacement questions from day one. The fan on the car, which stopped working, was actually a 2 wire with a silver resistor.

I got a replacement off an 06 CDTI to fit to my CDT and, without boring you with the details of seized fasteners, changed it all over, fan and cowling, control box and wiring.

But it did not work. I turned the ignition on to the second position and put on the demist, but nothing happened. Just to make sure, I started the engine, but still no fan rotation.

I opened up the control box again (I checked it first and the wiring is the same as the fan that came off - lots of jointed wires and different colours going all over the place) to see if I could meter any sense out of it, but there is 12V on practically everything.

The wiring looks very like the procedure detailed by Arctic and he does say all the switching is done on the negative side.

However, my idea that I would simply put 12v and a negative connection to the motor to make sure it was ok (presuming that the red wire is positive and the black is the negative) but from the meter testing I found there was 12v on both sides of the motor, both sides of the (new gold) resistor etc., and this stopped me in my tracks.

How do I test this lot? Any ideas welcome.

Best regards, Frank

T-Cut · 27th June 2017, 16:19

It could be the PCB is faulty. The circuit board is a weak spot in the diesel system. Maybe try swapping it with your old one? It's a regularly discussed topic and there is a repair service offered by FrechMike. Live feed to both motor leads is clearly wrong. I'd avoid connecting it till you know what's up. It could flatten the battery with 12v on the earth side.

TC

Stickman · 27th June 2017, 17:25

I've had some experience of duff fan on the diesel and went for the revotec kit
From Jules- I have to say it's the ultimate fit and forget solution
Easy to fit and wiring is simple enough too
Relatively cheap also
Regards
Chris

frankgoldstar · 27th June 2017, 17:44

Quote:

Originally Posted by T-Cut

It could be the PCB is faulty. The circuit board is a weak spot in the diesel system. Maybe try swapping it with your old one? It's a regularly discussed topic and there is a repair service offered by FrechMike. Live feed to both motor leads is clearly wrong. I'd avoid connecting it till you know what's up. It could flatten the battery with 12v on the earth side.

TC

Dear TC, I can swap the PCB, but as the old fan was not working, it is not like testing with a known good item.

I disconnected the whole lot once I found all the 12v live feeds.

As you say, 12v on both sides of the motor seems wrong for starters, but lacking any idea what the relays/PCB's and the colour changing wiring is supposed to do, I am a bit stuck.

I was wondering if a fan testing procedure existed so I could do a bit of metering.

Or at least a noddy explanation of how the thing is supposed to work.

I noticed the post from stickman with a certain amount of chagrin. I may well have got my hand in my pocket had I known what was in store!

Best wishes, Frank

SD1too · 27th June 2017, 19:31

Quote:

Originally Posted by frankgoldstar

As you say, 12v on both sides of the motor seems wrong for starters ...

Hello Frank, perhaps I can help.

12v on both sides of the motor simply means that there is no current passing through it.

12v on both sides of the gold resistor means that there is no current passing through that either.

This leads us to the conclusion that the low speed relay is not being energised.

Frank, are there three relays in your control box? The relay in the centre is the low speed relay. It should have thick grey wire and a thick black wire connections.

Remove the black wire terminal and wrap it in insulating tape.
Now remove the grey wire terminal and attach it to the relay pin from which you have just removed the black wire.

Now turn on the ignition and select windscreen demist.

Does the fan motor run now?

Simon

frankgoldstar · 27th June 2017, 21:30

Dear Simon,

many thanks for the information.

I do have three relays in the control box.

And indeed, there are the thick grey and black wires you describe.

I will go and try the procedure you describe tomorrow.

I was thinking that, without a reference, i.e. a ground being introduced, that there could be 12 volts on either side of the various bits, which would be in line with what Artic said, the switching being done on the negative side.

However, as a paid up coward, especially with low voltage, high current bits, I was very reluctant to do anything other than ask the good people of this site, most of whom seem to know a lot more than I do.

I was somewhat downcast, but this advice has given me a lift and renewed my purpose. thank you.

And for anybody who may wonder why auto electrical wiring worries me, many moons ago the backlight went out on my BSA. OK, only 6 volts, no need to worry.

I felt round under the frame and mudguard area and found the live wire end where it had parted company with the rest of the wiring - with the end of my finger, which pressed it to somewhere negative.

That wire heated up in an eyeblink and I spent the next few days looking ruefully at the white lines incised in my skin by the fine wires, spread by the pressure of my finger end.

Best wishes, Frank

frankgoldstar · 28th June 2017, 12:53

Dear All,

as it is currently raining steadily, but miserably here, I thought it best not to try to hook up my electrics on the uncovered car.

So instead, I tried to follow the wiring though with particular reference to the photos kindly posted by arctic.

I also looked more closely at the fan that I had taken off.

There is at least one difference between the one that came off and the one from the 06 CDT.

I have tried to attach a photo I took of the control box, but being a tecnophobe, all that goes into the post is a web address, no image.

https://scontent-lht6-1.xx.fbcdn.net...37&oe=59C973D2

I will persevere looking at the Arctic photos ans trying to compare them with my control box, but it is confusing to say the least.

Best wishes, Frank

frankgoldstar · 28th June 2017, 13:36

Quote:

Originally Posted by SD1too

Hello Frank, perhaps I can help.

12v on both sides of the motor simply means that there is no current passing through it.

12v on both sides of the gold resistor means that there is no current passing through that either.

This leads us to the conclusion that the low speed relay is not being energised.

Frank, are there three relays in your control box? The relay in the centre is the low speed relay. It should have thick grey wire and a thick black wire connections.

Remove the black wire terminal and wrap it in insulating tape.
Now remove the grey wire terminal and attach it to the relay pin from which you have just removed the black wire.

Now turn on the ignition and select windscreen demist.

Does the fan motor run now?

Simon

Dear Simon,

I looked again at the control boxes alongside each other, now that I have opened up the old one.

Right away I see on the "new" box of the CDTI, there are four flag connectors on all the four 1/4" spades on the PCB, but only three on the old one I took off my CDT.

The missing connector on the old box was the one in line with one of the the coil connections on the middle relay.

The centre relay has both the thick grey and black wires you mentioned going to it, so that looks fine, but as it is rather wet today so far, and the car is in the open, I have not tried to connect everything up again.

I have posted a photo of the CDTI control box in another post, but I will trace all the wires though properly now and scribble them down as some splices are not clearly shown.

Confusing all this.

Best wishes, Frank

SD1too · 28th June 2017, 14:49

Quote:

Originally Posted by frankgoldstar

Right away I see on the "new" box of the CDTI, there are four flag connectors on all the four 1/4" spades on the PCB, but only three on the old one I took off my CDT.

Frank, the link to a photograph in your 1.53 pm post works fine. With reference to this, which connector is missing on your CDT control box? Please describe it in terms of the cable colour code.
Is the missing cable tucked away out of sight somewhere? Is the missing cable present at one of the two chunky connectors which mate with the car's main loom?
Does the red/blue connector have two wires?

Simon

frankgoldstar · 28th June 2017, 18:22

Quote:

Originally Posted by SD1too

Frank, the link to a photograph in your 1.53 pm post works fine. With reference to this, which connector is missing on your CDT control box? Please describe it in terms of the cable colour code.
Is the missing cable tucked away out of sight somewhere? Is the missing cable present at one of the two chunky connectors which mate with the car's main loom?
Does the red/blue connector have two wires?

Simon

Dear Simon,

thanks for the continuing help.

I could have phrased it better, but the old control box is the one with four connectors on the PCB.

The "new" i.e. the one I am trying to fit only has three of the flag type receptacles fitted.

I have done a drawing showing the current wiring (as I found it) on the fan and control box I am trying to fit.

I will try to post that image as well.

And in case it helps, I can draw up the slightly different control box and wiring that I took off.

Best wishes, Frank

27th June 2017, 15:59	#1
frankgoldstar Avid contributor Rover 75 Conny Saloon Join Date: Sep 2009 Location: Manchester Posts: 144 Thanks: 16 Thanked 25 Times in 16 Posts	Fan replacement woes Dear All, I have to say first that I have been wrong on my fan replacement questions from day one. The fan on the car, which stopped working, was actually a 2 wire with a silver resistor. I got a replacement off an 06 CDTI to fit to my CDT and, without boring you with the details of seized fasteners, changed it all over, fan and cowling, control box and wiring. But it did not work. I turned the ignition on to the second position and put on the demist, but nothing happened. Just to make sure, I started the engine, but still no fan rotation. I opened up the control box again (I checked it first and the wiring is the same as the fan that came off - lots of jointed wires and different colours going all over the place) to see if I could meter any sense out of it, but there is 12V on practically everything. The wiring looks very like the procedure detailed by Arctic and he does say all the switching is done on the negative side. However, my idea that I would simply put 12v and a negative connection to the motor to make sure it was ok (presuming that the red wire is positive and the black is the negative) but from the meter testing I found there was 12v on both sides of the motor, both sides of the (new gold) resistor etc., and this stopped me in my tracks. How do I test this lot? Any ideas welcome. Best regards, Frank

27th June 2017, 16:19	#2
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,752 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	It could be the PCB is faulty. The circuit board is a weak spot in the diesel system. Maybe try swapping it with your old one? It's a regularly discussed topic and there is a repair service offered by FrechMike. Live feed to both motor leads is clearly wrong. I'd avoid connecting it till you know what's up. It could flatten the battery with 12v on the earth side. TC Last edited by T-Cut; 27th June 2017 at 16:22..

28th June 2017, 12:53	#7
frankgoldstar Avid contributor Rover 75 Conny Saloon Join Date: Sep 2009 Location: Manchester Posts: 144 Thanks: 16 Thanked 25 Times in 16 Posts	fan control box photo Dear All, as it is currently raining steadily, but miserably here, I thought it best not to try to hook up my electrics on the uncovered car. So instead, I tried to follow the wiring though with particular reference to the photos kindly posted by arctic. I also looked more closely at the fan that I had taken off. There is at least one difference between the one that came off and the one from the 06 CDT. I have tried to attach a photo I took of the control box, but being a tecnophobe, all that goes into the post is a web address, no image. https://scontent-lht6-1.xx.fbcdn.net...37&oe=59C973D2 I will persevere looking at the Arctic photos ans trying to compare them with my control box, but it is confusing to say the least. Best wishes, Frank

27th June 2017, 17:25	#3
Stickman Posted a thing or two Rover 75 saloon Join Date: Nov 2012 Location: Bordon Posts: 1,856 Thanks: 250 Thanked 403 Times in 352 Posts	I've had some experience of duff fan on the diesel and went for the revotec kit From Jules- I have to say it's the ultimate fit and forget solution Easy to fit and wiring is simple enough too Relatively cheap also Regards Chris

27th June 2017, 21:30	#6
frankgoldstar Avid contributor Rover 75 Conny Saloon Join Date: Sep 2009 Location: Manchester Posts: 144 Thanks: 16 Thanked 25 Times in 16 Posts	Dear Simon, many thanks for the information. I do have three relays in the control box. And indeed, there are the thick grey and black wires you describe. I will go and try the procedure you describe tomorrow. I was thinking that, without a reference, i.e. a ground being introduced, that there could be 12 volts on either side of the various bits, which would be in line with what Artic said, the switching being done on the negative side. However, as a paid up coward, especially with low voltage, high current bits, I was very reluctant to do anything other than ask the good people of this site, most of whom seem to know a lot more than I do. I was somewhat downcast, but this advice has given me a lift and renewed my purpose. thank you. And for anybody who may wonder why auto electrical wiring worries me, many moons ago the backlight went out on my BSA. OK, only 6 volts, no need to worry. I felt round under the frame and mudguard area and found the live wire end where it had parted company with the rest of the wiring - with the end of my finger, which pressed it to somewhere negative. That wire heated up in an eyeblink and I spent the next few days looking ruefully at the white lines incised in my skin by the fine wires, spread by the pressure of my finger end. Best wishes, Frank