Technical Ducato coolant fan order

[bluescuby]

Hi I have a ducato 2.3 2009 motorhome just back from France during the high temps.
Problem I had was on some of the extreme hills in a lower gear the temp. Gauge just reached just under 3/4 up and then shot up and temp. Red light came on 10 or so seconds later when I guess second fan came on gauge went down to halfway and was ok until another extreme hill.
So my question is I am thinking wiring the second fan so I can turn it on when getting hot.
So which is the first fan and which is second fan.
TIA

 

[Anthony489]

Hi

See the attached schematics. If you have AC fitted, the low speed fan can also run at even lower speed by switching in a series resistor. M is Brown, H is Grey and N is Black. The fans are controlled by the Engine Control Unit (ECU) via individual relays. The ECU gets information from the coolant temperature sensor (and the AC) and decides when and if to turn each fan on.

If you want to fit an override, I suggest fitting a separate fused relay with the contacts in parallel with the factory fit one. Bear in mind that engine cooling fans are "big hitters" in the current department. A 30 Amp or higher rated relay and thick cable is needed.