Cooling Fan Problem

[bigtone0777]

Hi again all, can anyone help me with the location of the fuse and relay for the cooling fan on my 2007 C4 Picasso 1.6 HDi?

I am only having an issue with the high speed side of the circuit so is this likely to be a problem with the resistor or does it have separate circuits for low and high speed? Diagbox is reporting and open on the high speed circuit.

Thanks in advance.

Tony

[GiveMeABreak]

The system is controlled by an electronic control unit item (6) inside the fan housing under a cover. That is supplied by a 60A Fuse (F12) in the main supplies protection unit.

It is a single fan 2 speed system all controlled by the engine ECU. The relay is internal to the engine fuse box and not really user serviceable.

[GiveMeABreak]

Here's the circuit specific to your vehicle:



1522 IS the electronic Control Circuit for the Fan.
1320 Is your Engine ECU

1514 : fan control /
1550 : fan control 2 (-)
1590 : Fan unit relay power supply
1599 : Fan unit diagnostic info
1540 : fan control 1 (-)

[bigtone0777]

Thanks for that Marc. It's looking likely to be a broken wire or a green and crusty connector as the both speed share the same power and grounds I'm guessing and probably between the fan itself and the 1550 on the diagram.

[white exec]

From that circuit, the engine ECU #1320 can send two outputs to #1522 Control Unit, for Lo and Hi speed fan operation.
1522 essentially contains two relays, one for each speed, and one dropper resistor for Lo speed.

Shouldn't be difficult to chase the missing fault through.
Fault might just be that 1522 needs replacing.
Loss of just high speed suggests that the HS relay (or its contacts) have given up/become arc-damaged.
These contacts will have hard time, given that the fan is fused at 60A!

[bigtone0777]

As the low speed works fine the issue has to be with either 1540z or 1599z between ECU (1320) and fan control unit (1522). I'm guessing 1514B to the fan is fine as it is also used for the low speed feed. Does my logic seem correct?

[white exec]

Apart from the relays and the main dropper resistor, there are also two smaller components inside the 1522 control unit - a variable resistor, and what is shown as a fuse.
I'm unsure about the exact functions of these two.
Apart from checking the signals arriving from engine ECU, it might be worth replacing 1522 (price?) to eliminate it.

Engine ECUs rarely give problems, but fan-switching relays, and high-current dropper resistors, do.

[bigtone0777]

If the low speed hadn't been working I'd have put money on the dropper resistor but the's obviously doing it's job. I'd have a look for control unit (1522) but I don't even know it's correct name to even search it

[bigtone0777]

I think this could be it, I thought that was just a resistor for the low speed but it has the right amount of connectors, the high speed must pass through this but bypass the resistor. For the price it's worth loading it into the parts cannon

https://www.ebay.co.uk/itm/113037563500 ... 1nEALw_wcB

[bigtone0777]

I'm not sure if this is the culprit but it looks like it's been in the elements for a very long time and it's a genuine part so the chances are it could be original. I'll replace it anyway and see if it solves the problem. I think there is an internal relay for the two speeds so worth a try

[white exec]

The item is called "Cooling Fan Electronic Control Unit", but there are several of those devices fitted to various models, with similar appearance.
If you could post your VIN, we can look up the correct part number.

[bigtone0777]

I have the part number from the part itself (provided it's the correct part fitted!)

The VIN is VF7**************[VIN obfuscated, can be read by forum staff]

[GiveMeABreak]

Already have the VIN.

The control unit has been superseded with a new part (9830143880) for the unit and (1308CX) for the cover. Citroen specify both parts required, so I suspect the replacement unit is different and won't fit the previous unit's cover.

Items are priced at £81.63 and £4.62 for the cover inc. VAT direct from Citroen.

[white exec]

The earlier part was 1308.CW (replaced by 98301....), just in case you go looking for a secondhand replacement.
________

Seems a shame that almost all of the single fan installations rely on a high-wattage dropper resistance to produce slow speed - not helped by often being located in a position (for added air-flow) prone to weathering. This dates back to at least the early '80s.
Not a criterion for choosing a car, I know, but at least the twin-fan models have the benefit of using the much more efficient (resistor-less) arrangement of relays, to give series (low speed) and parallel (high speed) running.

[bigtone0777]

Thanks for the info guys