rad fan override switch

janrangie · Post by **janrangie** » 06 Nov 2018, 05:03

Hello, 2002 V70 XC70 2.4T gearmatic, how/where to fit radiator fan override switch? reason - towing biggish caravan and fan manual control will be of great assistance on long inclines (hot climate in South Africa), if manually can switch fan on earlier rather then wait for ecu commanding on/off sequence. Currently fan goes on too late and experiencing overheating, same sometimes happening in slow moving traffic. please assist.
kind regards
Jan

Post by **oragex** » 06 Nov 2018, 10:59

How does the fan unit looks? Does it have a 10x5cm square metal box on it? That's the controller, maybe hot wire it and attach a switch

Don't forget, you still have to refresh the fluid now and then when towing, with the 3309 type (not sure it's the correct one for the geartronic unit, just ask maybe here https://www.volvoforums.org.uk/forumdisplay.php?f=19). Maybe a 3.5L sump drain and refill by the dipstick tube every 2-3000km or so in hot weather. Do not replace all fluid at once (capacity is 7L)

Post by **June** » 06 Nov 2018, 11:13

To cause the fan to continuous run with the engine on and stop with the engine off you attach a jumper wire to the relay ground for the high speed and the fan will then always run in the high speed. It is safer than running a switch and bypassing the factory wiring. June

janrangie · Post by **janrangie** » 07 Nov 2018, 13:54

June wrote: 06 Nov 2018, 11:13 To cause the fan to continuous run with the engine on and stop with the engine off you attach a jumper wire to the relay ground for the high speed and the fan will then always run in the high speed. It is safer than running a switch and bypassing the factory wiring. June

Hi, not sure if '02 having a fan relay? just the controller (under correction here)
regards
Jan

janrangie · Post by **janrangie** » 08 Nov 2018, 06:09

: volvo-v70-elektrinis-radiatoriu-ventiliatorius3.jpg (115.05 KiB) Viewed 2553 times

oragex wrote: 06 Nov 2018, 10:59 How does the fan unit looks? Does it have a 10x5cm square metal box on it? That's the controller, maybe hot wire it and attach a switch

Don't forget, you still have to refresh the fluid now and then when towing, with the 3309 type (not sure it's the correct one for the geartronic unit, just ask maybe here https://www.volvoforums.org.uk/forumdisplay.php?f=19). Maybe a 3.5L sump drain and refill by the dipstick tube every 2-3000km or so in hot weather. Do not replace all fluid at once (capacity is 7L)

Post by **abscate** » 08 Nov 2018, 06:56

Jan - I would fix your cooling system before I put in more stuff to fix an overheating problem.

Coolant changed every two years

Pressure test system - it should hold 16 psi of pressure, check reservior and cap

50/50 mix of glycol/water

check ECT (temperature sensor ) for correct resistance.

Post by **jimmy57** » 08 Nov 2018, 07:30

There is not a switch and wire solution for the controller that is signalled by a PWM control signal. If you added a relay by splicing into the wires between controller and the fan motor you might kill the controller.

Xc70 of that year range run hot when towing grades if the octane of fuel is too low. The low octane causes spark knock and the ECM gets knock sensor signalling reporting the knock and ECM retards timing a lot. The late ignition timing will cause the bulk of the combustion flame to occur after TDC and expose more heat to cylinder wall where it is passed into coolant more readily.
What fuel are you using? I think South Africa petrol is available in higher octane levels.