Rad fan manual override switch

jroz · Nov 7th, 2018, 20:17

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

Brendan W · Nov 7th, 2018, 21:23

Hi Jan
My gut says there is something wrong with the cooling system. Rad fins blocked, stat not opening fully, fan not seeing full speed signal.
How does the temperature gauge behave in normal driving?
As for a bypass I'm not even sure it's possible with those fans on pulse width modulation for speed control.

jroz · Nov 8th, 2018, 13:52

Hi Brendan
some observations:
ac on - fan goes on low at 55 deg C
stat start opening at +- 92 deg C
ac off normal running fan go on low at +- 96 deg C
temp read 108 deg C fan go on high, go off at +- 96 deg C (in city traffic)
new radiator fitted, cooling system flashed ( found overflow bottle small dia outflow blocked with rubbish, cleaned and it seems local pressure build up being sorted)
taken t/stat out to test coolant flow, water pump seems to work ok, engine idle and at 2000 rpm, coolant temperature stay between 74 - 90 deg C
mind you not tested towing trailer only in traffic, seems better,
concern: cant drive with out t/stat as once coolant get hotter its difficult to cool off due to circulation speed, its not being controlled.
t/stat - start opening at 93 deg C, think its too high ??
Think ? if cannot fit override switch to fan high speed ?? how to change ac fan on from low to high speed?
another observation is that rad fan does not having relays?? maybe I am wrong here...
your input appreciated
regards
Jan

jroz · Nov 8th, 2018, 13:57

the temperature gauge sit in 12 o'clock position from about 68 deg C , its really useless piece of equipment.........

MarvinMitt · Nov 8th, 2018, 16:24

Quote:

Originally Posted by jroz

Think ? if cannot fit override switch to fan high speed ?? how to change ac fan on from low to high speed?
another observation is that rad fan does not having relays?? maybe I am wrong here...

Pulse-width modulation doesn't work like that.
If you're interested, then search and you will find.

The ECU monitors the coolant temperature and depending how much it exceeds the desired working temperature, it will alter the PWM signals duty cycle (0-100%) sent to radiator control module to get desired fan speed.

In this video, the ECU is replaced with a calibrated PWM generator.

https://www.youtube.com/watch?v=i6go2VTr5bY

Brendan W · Nov 8th, 2018, 20:18

Is the thermostat opening fully ?
The manual I have gives 90C opening starts and 105C fully open.
I imagine that there are variations for different markets.

jroz · Nov 9th, 2018, 17:00

Hi Brendan, yes my is similar, start opening at 93C and is fully at 108C at which point the fan goes to high speed mode, sometime its OK and the coolant temperature drop fast, depend on driving situation, highway or city driving but its crazy as the stat working overtime all the time......... maybe the volvo is not so good in towing trailers....
thanks
jan

cheshired5 · Nov 9th, 2018, 17:35

I think you have a circulation problem.
When the engine is starting to overheat carefully check the temperature of all coolant hoses.
If the system is unable to maintain temperature and overheating, all hoses should be too hot to hold.
If one hose is significantly cooler, it obviously isn't carrying 100°C coolant so the hose or something before it is blocked.
The small diameter hose linking the top of the radiator to the expansion tank would be my first suspect followed by the lower radiator hose and heater hoses but check everything.

Brendan W · Nov 9th, 2018, 18:37

Is it possible that the water pump was replaced with something non Volvo and that it doesn't have the same ooomph. Reaching a bit but that car should tow a caravan to Hell and back.
Could the fins in the intercooler and/or the a/c condenser be clogged and restricting airflow?
Is the undertray still fitted? Dealer here swore they just make things too hot.

MarvinMitt · Nov 9th, 2018, 20:39

+1 on the water pump

https://www.youtube.com/watch?v=I6MkBufU8yU&t=53s

Nov 7th, 2018, 20:17	#1
jroz New Member Last Online: Nov 26th, 2018 18:02 Join Date: Nov 2017 Location: illovo beach	Rad fan manual override switch 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

Nov 8th, 2018, 13:52	#3
jroz New Member Last Online: Nov 26th, 2018 18:02 Join Date: Nov 2017 Location: illovo beach	Hi Brendan some observations: ac on - fan goes on low at 55 deg C stat start opening at +- 92 deg C ac off normal running fan go on low at +- 96 deg C temp read 108 deg C fan go on high, go off at +- 96 deg C (in city traffic) new radiator fitted, cooling system flashed ( found overflow bottle small dia outflow blocked with rubbish, cleaned and it seems local pressure build up being sorted) taken t/stat out to test coolant flow, water pump seems to work ok, engine idle and at 2000 rpm, coolant temperature stay between 74 - 90 deg C mind you not tested towing trailer only in traffic, seems better, concern: cant drive with out t/stat as once coolant get hotter its difficult to cool off due to circulation speed, its not being controlled. t/stat - start opening at 93 deg C, think its too high ?? Think ? if cannot fit override switch to fan high speed ?? how to change ac fan on from low to high speed? another observation is that rad fan does not having relays?? maybe I am wrong here... your input appreciated regards Jan Last edited by jroz; Nov 8th, 2018 at 14:02.

Nov 8th, 2018, 20:18	#6
Brendan W Premier Member Last Online: Apr 2nd, 2024 19:50 Join Date: Dec 2007 Location: Wexford	Is the thermostat opening fully ? The manual I have gives 90C opening starts and 105C fully open. I imagine that there are variations for different markets. Last edited by Brendan W; Nov 8th, 2018 at 20:30.

Nov 9th, 2018, 17:35	#8
cheshired5 Premier Member Last Online: Dec 26th, 2021 13:42 Join Date: Dec 2013 Location: Crewe	I think you have a circulation problem. When the engine is starting to overheat carefully check the temperature of all coolant hoses. If the system is unable to maintain temperature and overheating, all hoses should be too hot to hold. If one hose is significantly cooler, it obviously isn't carrying 100°C coolant so the hose or something before it is blocked. The small diameter hose linking the top of the radiator to the expansion tank would be my first suspect followed by the lower radiator hose and heater hoses but check everything. __________________ 2002 S60 SE D5 Manual 209000 miles

Nov 9th, 2018, 20:39	#10
MarvinMitt Senior Member Last Online: Nov 1st, 2021 21:18 Join Date: Sep 2016 Location: Tartu	+1 on the water pump https://www.youtube.com/watch?v=I6MkBufU8yU&t=53s __________________ 2002 V70 D5

Nov 7th, 2018, 21:23	#2
Brendan W Premier Member Last Online: Apr 2nd, 2024 19:50 Join Date: Dec 2007 Location: Wexford	Hi Jan My gut says there is something wrong with the cooling system. Rad fins blocked, stat not opening fully, fan not seeing full speed signal. How does the temperature gauge behave in normal driving? As for a bypass I'm not even sure it's possible with those fans on pulse width modulation for speed control.

Nov 8th, 2018, 13:57	#4
jroz New Member Last Online: Nov 26th, 2018 18:02 Join Date: Nov 2017 Location: illovo beach	the temperature gauge sit in 12 o'clock position from about 68 deg C , its really useless piece of equipment.........

Nov 9th, 2018, 17:00	#7
jroz New Member Last Online: Nov 26th, 2018 18:02 Join Date: Nov 2017 Location: illovo beach	Hi Brendan, yes my is similar, start opening at 93C and is fully at 108C at which point the fan goes to high speed mode, sometime its OK and the coolant temperature drop fast, depend on driving situation, highway or city driving but its crazy as the stat working overtime all the time......... maybe the volvo is not so good in towing trailers.... thanks jan

Nov 9th, 2018, 18:37	#9
Brendan W Premier Member Last Online: Apr 2nd, 2024 19:50 Join Date: Dec 2007 Location: Wexford	Is it possible that the water pump was replaced with something non Volvo and that it doesn't have the same ooomph. Reaching a bit but that car should tow a caravan to Hell and back. Could the fins in the intercooler and/or the a/c condenser be clogged and restricting airflow? Is the undertray still fitted? Dealer here swore they just make things too hot.

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