Manual switch for radiator fan bypass.

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seanrx
Donor 2021
Posts: 95
Joined: 02 Feb 2017, 13:11
x 4

Manual switch for radiator fan bypass.

Post by seanrx »

Hi all.

To put a cooling fan switch onto the dashboard, anyone wired this with good results?

My car is a C5 mk2. One fan and one relay.

On YouTube,some easy to follow vids.

Two switch wires, one to ground and other to relay. And that's really all to do?
wheeler
Posts: 5279
Joined: 21 Sep 2002, 19:07
x 320

Re: Manual switch for radiator fan bypass.

Post by wheeler »

Just curious why you need this? Are you masking a fault? Is the fan operating normally?
seanrx
Donor 2021
Posts: 95
Joined: 02 Feb 2017, 13:11
x 4

Re: Manual switch for radiator fan bypass.

Post by seanrx »

So, I tried this today.

Fail.
17 amp wire into relay 85 and then into 86, just to be sure.
Even ran the engine for more juice. Fan didn't move.
For a 3 speed fan 'chopper fan' , perhaps this mod is not ideal?

Last week I spent £54 for a one hour diagnostic with no success. I didn't want to pay for more hours.

A fan with just one speed will be more than I have now! Can this be done, just bypass all the 3 speed settings?
wheeler
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Joined: 21 Sep 2002, 19:07
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Re: Manual switch for radiator fan bypass.

Post by wheeler »

wheeler wrote:
14 Jul 2021, 10:17
Just curious why you need this? Are you masking a fault? Is the fan operating normally?
If you give us a bit more info like what is working or not working it may be easier to help or offer advice.
Does the fan work at all? does it come on when you operate the A/C?
What happens if you unplug the coolant temp sensor with the engine running?
seanrx
Donor 2021
Posts: 95
Joined: 02 Feb 2017, 13:11
x 4

Re: Manual switch for radiator fan bypass.

Post by seanrx »

Wheeler.
Hi. Can you search my forum posts?

My 'Febi to Citroen numbers' has all my cooling probs and woes

Unplug of coolant sensor is the only time the fan will run. Full pelt.
admiral51
Donor 2021
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Joined: 24 May 2007, 10:11
x 300

Re: Manual switch for radiator fan bypass.

Post by admiral51 »

seanrx you are a donor to this forum, so please post your Vin number up which will be masked and only visible to Forum Admins ( look at my sig on the left ) and i am sure we as a forum can help.
Each vehicle may have different wiring ECU controlled functions so post your Vin and i am sure someone on here will be able to offer advice and things to look at specific to your vehicle

Colin
admiral51
Donor 2021
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Joined: 24 May 2007, 10:11
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Re: Manual switch for radiator fan bypass.

Post by admiral51 »

Okay just looked again you have a MK11 C5 and there is another thread about the cooling fan issue.
Can you repost here your issues along with your Vin number as without both it is very hard to pin point what the issues are
seanrx
Donor 2021
Posts: 95
Joined: 02 Feb 2017, 13:11
x 4

Re: Manual switch for radiator fan bypass.

Post by seanrx »

Hi.
VF7**************[VIN obfuscated, can be read by forum staff].

Fan never works, even when ac is on.
It works only when I unclip the coolant sensor harness.

All chassis earths, I cleaned them for the mechanics diagnostic.
wheeler
Posts: 5279
Joined: 21 Sep 2002, 19:07
x 320

Re: Manual switch for radiator fan bypass.

Post by wheeler »

OK Basics first. Have you checked all the fuses? Particularly Fuse 1 in the under bonnet fuse box?
Looks like you have a 'chopper' fan set up. Do you have a good battery supply at pin 1 of the big 2 way plug & a good earth at pin 2?
Id next be looking at live data of the coolant temp sensor & see if the ECU is trying to switch the fan on at the lower speeds.
Here is a diagram.
Attachments
C5II cfan.jpg
seanrx
Donor 2021
Posts: 95
Joined: 02 Feb 2017, 13:11
x 4

Re: Manual switch for radiator fan bypass.

Post by seanrx »

Thanks, but this is old info for me. I've done all the fuse and maxi fuse checks and ohms and signal feed on the harnesses.
And I won't pay for more live feed at garage.

Really, I want to use this post for new wiring in fan, that's all.
admiral51
Donor 2021
Posts: 2379
Joined: 24 May 2007, 10:11
x 300

Re: Manual switch for radiator fan bypass.

Post by admiral51 »

The fan is controlled by both the engine ECU and the A/C ECU and i also believe to some degree by the BSI.
Feel free to run via an internal cabin switch to a relay and an inline fuse to bypass the current set up to switch on and off as you want.
The wiring diagram is above but people here are trying to help solve the issue you have.
The fan works when you unplug the stat plug so the fan works but it does have a number of relays (3 i think ) so it could be an issue with one of them

Just saying thats all
seanrx
Donor 2021
Posts: 95
Joined: 02 Feb 2017, 13:11
x 4

Re: Manual switch for radiator fan bypass.

Post by seanrx »

Hi.

Relays, only one, wired on between the fan and power plug.

It's a new fan and I have tested its relay. I still have the old unit. That relay, no rattle when shook, so I'll start with this.
(Its motor burnt out)

Just want a cheaper option than £54 per hour diagnostic (not with Lexia) then to be told £s more for actual repair.

Car's worth less than a grand.