Hi, I have seen a few posts about radiator cooling fans not coming on but I cannot seem to locate the temp sensor/switch.
When I am going up long/big hills in my Laika motorhome the temp gauge goes above half but returns to "normal" as soon as I going downhill or driving on the flat. I have tested both fans with a 12v source and they both work well. There is a black box on top of the radiator which contain the relays for the fans, they both seem OK. I can measure 12v on the positive side to chassis on each fan so looks like the negative is switched to ground via the relay which get a control voltage from the management system (wherever that is!) which in turn gets a "signal" from the temp sensor. I have read on other posts that the sensor is screwed to the radiator near the bottom hose, I cannot see one so now I am stuck. I think it has an Iveco engine fitted if that is any help.
Cheers,
Eric

Like you, I like to know whether components are working as they should.
Like you I have a 2.8JTD motorhome conversion. You've probably got a hot water calorifier in the habitation area which heats up from the engine, and a 'blown air'? heating system,-Eberspacher possibly.
When these are installed, the normal radiator sensor wiring seems to be disconnected and re-routed somehow. Engine cooling still works however. The sensor plug on the bottom of my radiator,-the one with a big brass 29mm. hexagonal nut on my van is not connected to anything. I've only ever had the rad. fans come on after sustained 2nd. gear climbing for about 15 mins. The 2.8 has a huge radiator. I've never driven in very hot climates, maybe its different then. The needle never travels over half way between cold and hot however I drive.

Hi, I have no idea what a hit water calorifier is. I cannot see any large brass nut on the radiator, whereabouts is it on yours?

Something like this? http://www.ebay.co.uk/itm/Fiat-Ducato-2-3-2-8-JTD-3-0-D-Water-Coolant-Temperature-Sensor-New-46472179-/310995454129
My sensor is at the bottom left of the rad, looking from behind, i.e. UK nearside.
A calorifier is just like a small domestic immersion heater tank, connected to your engine cooling system? http://www.ebay.co.uk/itm/10-Litre-VERTICAL-Surecal-Calorifier-calorifiers-water-heater-/361562480831

blaven said:

Something like this? http://www.ebay.co.uk/itm/Fiat-Ducato-2-3-2-8-JTD-3-0-D-Water-Coolant-Temperature-Sensor-New-46472179-/310995454129
My sensor is at the bottom left of the rad, looking from behind, i.e. UK nearside.
A calorifier is just like a small domestic immersion heater tank, connected to your engine cooling system? http://www.ebay.co.uk/itm/10-Litre-VERTICAL-Surecal-Calorifier-calorifiers-water-heater-/361562480831

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Thanks for that, there is no heater of that type in the motorhome. The home has hot air heating but comes from the hot water heater. I cannot see any sensor on the near side of the radiator. I assume it would be on the back of the rad not the front. There are no cables coming out of the rad area so I am guessing the sensor must be on the engine block somewhere?

If it's any help you can check the fan operation from within Multieuscan software via the control activation function for checking various circuits and instruments etc.
Like others, I've never heard the fans running despite fully loaded hill climbs and lengthy periods in traffic and can only put it down to the large coolant volume and lower diesel engine heat dissipation. Maybe they designed it based on summer Italian temperatures! I stick some cardboard over the radiator in the winter to try and get the motorhome heater going.

toyogran said:

If it's any help you can check the fan operation from within Multieuscan software via the control activation function for checking various circuits and instruments etc.
Like others, I've never heard the fans running despite fully loaded hill climbs and lengthy periods in traffic and can only put it down to the large coolant volume and lower diesel engine heat dissipation. Maybe they designed it based on summer Italian temperatures! I stick some cardboard over the radiator in the winter to try and get the motorhome heater going.

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Mmm, no idea what Multieuscan software or the control activation is. The temp gauge has gone over half way recently when climbing big hills and sat in traffic on a warm day (30 C) day. It soon came down again, just a bit worried that if am sat in a traffic jam and it starts to overheat and the fans don't turn on.

Multieuscan is a software package which "talks" well with pre obd2 Fiats. Mine is about 2005 vintage and it works fine with the dongles that plug into the diagnostic port. You load the actual software onto a Windows computer.
Speak to Gendan.co.uk they are very helpful. Within the software you can run tests on things like instruments, dash lights and cooling fans etc and get live data. Someone on this forum has mentioned using AlfaOBD app on a mobile phone with a Bluetooth dongle but don't know if you can activate the fans etc.
You can get a free version of Multieuscan which has limited functionality. Hope this helps.

I had a similar issue and I found the problem was the female connector pins that connected to the switch at the bottom of the rad. Initially the connectors 'looked' ok but closer inspection showed that the part that grips the male pin had rusted off and disappeared, hence a very loose fit. I removed the sensor and soldered new wired on to the pins, sleeved them, refitted the sensor and then crimped the new wired to the loom wires.

The fans should run if you just leave the engine idling for long enough.

andytw

andytw said:

I had a similar issue and I found the problem was the female connector pins that connected to the switch at the bottom of the rad. Initially the connectors 'looked' ok but closer inspection showed that the part that grips the male pin had rusted off and disappeared, hence a very loose fit. I removed the sensor and soldered new wired on to the pins, sleeved them, refitted the sensor and then crimped the new wired to the loom wires.

The fans should run if you just leave the engine idling for long enough.

andytw

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Thanks for that. The problem is I cannot see any sensor fitted to the radiator. I have crawled under the vehicle and I cannot see any wiring loom coming from the radiator only the ones that go to the fans. If you still have the vehicle and could take a pic and post it on the forum that would be great.
Eric

andytw said:

I had a similar issue and I found the problem was the female connector pins that connected to the switch at the bottom of the rad. Initially the connectors 'looked' ok but closer inspection showed that the part that grips the male pin had rusted off and disappeared, hence a very loose fit. I removed the sensor and soldered new wired on to the pins, sleeved them, refitted the sensor and then crimped the new wired to the loom wires.

The fans should run if you just leave the engine idling for long enough.

andytw

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Just a had a look on eper and for the model/type I have the switch/sensor isn't fitted to the radiator. No idea how the fans are supposed to turn on! Might be something to do with it being a motorhome?

UPDATE.
I have researched eper and there is a coolant temperature sensor mounted on the thermostat housing on my particular type of 2.8 JTD , part number 99455420. anyone know if this is the sensor for the temp guage or would this be the sensor to tell the management system to turn on the fan/s?

Erc1958 said:

UPDATE.
I have researched eper and there is a coolant temperature sensor mounted on the thermostat housing on my particular type of 2.8 JTD , part number 99455420. anyone know if this is the sensor for the temp guage or would this be the sensor to tell the management system to turn on the fan/s?

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Simple things first. Have you checked that the fans aren't seized - common problem, turn them by hand (ignition off) to check. Have you got 12V at the fans afaik the relay switches the earth.

corcai said:

Simple things first. Have you checked that the fans aren't seized - common problem, turn them by hand (ignition off) to check. Have you got 12V at the fans afaik the relay switches the earth.

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Yep, done all that. If you look at my original post, there is 12v on the fans. 12v to the relays and if I disconnect the fans and apply 12v direct the fans turn no problem.

Erc1958 said:

Yep, done all that. If you look at my original post, there is 12v on the fans. 12v to the relays and if I disconnect the fans and apply 12v direct the fans turn no problem.

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Sorry missed that was on the phone browser earlier.

You can test the temp sensor its an NTC should be around 2k Ohms at 25C and 300 Ohms at 80C.

corcai said:

Sorry missed that was on the phone browser earlier.

You can test the temp sensor its an NTC should be around 2k Ohms at 25C and 300 Ohms at 80C.

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OK thanks for the info. My next quest is to locate the sensor. I have had a look and so far with no joy. Looks like it is on the thermostat housing but I can't even locate that as yet!

corcai said:

Sorry missed that was on the phone browser earlier.

You can test the temp sensor its an NTC should be around 2k Ohms at 25C and 300 Ohms at 80C.

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UPDATE.
O.K. there are two "sensors" mounted to the thermostat housing on eper one is listed as a sensor and one as a "sender" I removed the sensor, tested it and it tested as you suggested above. However the sender is open circuit when cold or hot. The part number is 4837950 which if I Google comes up with coolant temperature sensor so I assume this is the problem? Also does anyone know which coolant I should use as most of the coolant drained when I removed the sensors(s). Cheers

FURTHER UPDATE:
On further investigation on the make up of the sender, I was testing it incorrectly. The body of the sender is the negative connection. The two spade terminals have 12v and approx 7v on them. Looking at onlinecarparts.co.uk site regarding this sender there is a little diagram on how it works. Part number 4837950. I ended up shorting both connections and at the same connected them to ground. Fans still didn't turn but a little red thermometer symbol appeared on the dash display, not the temp gauge, that didn't move. Now I am at a loss on what to look for next. Can't seem to find any other sensor near or on the cooling section of the engine. Any further help from anyone would be greatly appreciated.
Cheers

That a combined ntc and switch, the switch operates at 107c to put on the light, the ntc is between one of the terminals and the body.

corcai said:

That a combined ntc and switch, the switch operates at 107c to put on the light, the ntc is between one of the terminals and the body.

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Yes, I thought that was the case, but I have shorted both terminals to the chassis and the only thing that happened was the temp light came on. When I took the sender out and applied heat via a heat gun and measured the resistance across the terminals the resistance went to zero when the unit got hot ( didn't know what temperature it was) so I thought shorting both terminals to the chassis one by one and then both at the same type would turn the fans on, it didn't. There must be another temp sensor/ sender somewhere but I cannot find it.