Cooling Fans

[cossie]

Anyone know how to connect up two cooling fans.I have two fitted but only one that works.

[Toddman]

If it has not been discussed on this forum Clive it is definitely over on the old one but I seem to think that most of the valvers have the second fan wiring present so if you fit a second item you just plug it in.

IIRC the second fan was a towing accessory so makes sense for the wiring to be in the loom and fitting the accessory just a case of bolting in and plugging the wires together.

Cheers
Luke

[Vanny]

Mk1 Pug 405 diesel or Pug 309 diesel wiring loom is the way to go, you then get high power and relay control on a completely seperate loom and fuse.

Alternatively you can fit the Aircon fan loom from a european BX with AC if you can find someone who will supply it.

Citroen did do an accessory wiring kit which plugs in but has no relays. The actual circuit for these is quite simple but i no longer have a copy. Is there a wiring diagram in the workshop documents?

[prm]

There’s quite a few ways you can wire-up twin fans by utilizing the existing half speed resistor, but found these can get bl- -dy hot stationary.

If the twin fan electrical connections are not there, a drawing that may help, using std. BX relays, mounted slightly forward of the LHM tank on the vertical inner wing.

http://i295.photobucket.com/albums/mm15 ... fans_1.jpg

You can incorporate a fan run-on set-up by fitting an additional relay onto the bulkhead relay rail with a fused direct feed from the battery.

If you can understand my electrical hieroglyphics !! a drawing of mods that indicate the run-on wiring

http://i295.photobucket.com/albums/mm15 ... ods1_1.jpg

Not sure if I’ve added the links to the post correctly?? If they fail to come up, let me know, will PM.

Regards

[Mike E (uk)]

If you had air con, you would already have 2 fans.

to wire in 2nd fan:

wire the new fan in parallel with existing fan.

wire a second low speed dropper resistor in parallel with the existing resistor.

job done.

both fans now spin at the correct low speed when engine is hot, and both spin at high speed when engine is very hot.



Engine temp should now sit constantly at 90 degrees, unless your rad or thermostat are faulty.

Mike

[Vanny]

If you had air con, you would already have 2 fans.

exactly why using the LOOM from such a car on a single fan car would be beneficial.

I'm personally of the belief that using relays (which swap the fans between parallel and serial) is a much better system as it won't waste so much engine power at low speed. Power consumption is pretty similar between low and high speed using a resistor, and the current draw will effect engine performance, though it can be argued that the fans would only come on at slow speed in which case whats a few BHP.

A standard 75 amp Mitsubishi alternator from an A/C equipt BX, and a Bosch silver line 6PN (Xantia diesel) car battery fully charged will last approximately 15 minutes at motorway speeds with a relay twin fan setup. I would guess that a regular Valeo 50Amp alternator coupled to the correct (smaller) battery for a 16v would probably supply power for considerably less time when powering a set of fans (regardless of relay setup or resistor). What i'm getting at is IF you need twin fans (and i am of the belief that for normal day to day driving of a 16v you should not) then you would be strangely advised to get a bigger battery and bigger rated alternator.

I've also found that the resistors burn out quite regulalry and i think this is as a result of water ingress breaking down the contact and leading to current fluctuations in the resistor, causing them to fail prematurely. I think there are sources of as new resistors.

[prm]

Vanny,

I,m inclined to agree with you with ageing fan resistors possibly failing due to the accumulation of corrosion building up on the contacts. The OE position is not the best all weather place!! They must have placed it there for cooling the unit??


I’ve modified 16v’s with a twin fan set-up, utilizing relays rather than resistors. Because, you will no doubt find, the supply cable internal copper wire strands, adjacent to the resistor, are blackened due to excess overheating, but must admit only ever had one that had failed - over 160k.

Also found a more precise engine temperature control using relays, with the thermal switch having a consistent amp/voltage supplies rather than fluctuating with the resistor and terminals over heating.

Regards P

[cossie]

Think I'll leave it with one.
I havent got any idea when it comes to wiring drawings.

[Vanny]

If you remind me around christmas then i can probably make up a plug in loom if that would help? There mostly standard connectors and i can probably do it as a set including relays, fuses and thermostat (diesel) for not a lot of money. At the moment though i dont have access to anything car related (manuals, wiring, spares etc)

[cossie]

Ok
thanks Vanny.I'll try to remember.