Technical Cooling fans not working

[Skindiga]

Hi guys, currently travelling in a
2001 Fiat ducato 1.9TD swift sundance motorhome
Bought it a year ago and done a lot of work to it to minimise work on travel.
Never heard the fans come on and when we were in Dartmoor forest the temp gauge went almost into the red and I had to pull over and stop. (Fans still not engaging)
Have done various test.
Tested relays- all good.
Jumped loom connectors for CTS with wire and both fans work.
I don’t have the best multimeter so can’t get reading from CTS (have a new one also no reading) so probably a multimeter problem as temp gauge on dash works fine.
It’s had a new radiator and checked all wiring which looks good.
Check fuse- all good.

Not sure what the problem could be
Any advice would be much appreciated.

Many thanks
Stuart

 

[ninian324]

Most likely a faulty thermostat that controls the fans.

 

[Skindiga]

Most likely a faulty thermostat that controls the fans.

Thanks very much!
Much appreciated

 

[Communicator]

Hi guys, currently travelling in a
2001 Fiat ducato 1.9TD swift sundance motorhome
Bought it a year ago and done a lot of work to it to minimise work on travel.
Never heard the fans come on and when we were in Dartmoor forest the temp gauge went almost into the red and I had to pull over and stop. (Fans still not engaging)
Have done various test.
Tested relays- all good.
Jumped loom connectors for CTS with wire and both fans work.
I don’t have the best multimeter so can’t get reading from CTS (have a new one also no reading) so probably a multimeter problem as temp gauge on dash works fine.
It’s had a new radiator and checked all wiring which looks good.
Check fuse- all good.

Not sure what the problem could be
Any advice would be much appreciated.

Many thanks
Stuart

I am struggling with the apparrently unexplained abbreviation "CTS".
Are you perhaps referring to the thermostatic switch on the radiator? A thermostatic switch should be either open or closed.
The temperature gauge is separate to the fan operation, with the thermistor sensor being located near the engine thermostat.

 

[Skindiga]

CTS
Coolant temperature sensor
On the bottom near side of the radiator
Thanks

 

[Communicator]

CTS
Coolant temperature sensor
On the bottom near side of the radiator
Thanks

In other words just a fancy name for the thermostatic switch. My Talbot Express had a dual contact thermostatic switch, with one switch closing at a higher temperature to operate the second fan. This switch should not be confused with the temperature sensor for the gauge. My 2.8jtd has two sensors, one for the gauge, and a second one for the ECU, which also controls the fans.

 

[Skindiga]

In other words just a fancy name for the thermostatic switch. My Talbot Express had a dual contact thermostatic switch, with one switch closing at a higher temperature to operate the second fan. This switch should not be confused with the temperature sensor for the gauge. My 2.8jtd has two sensors, one for the gauge, and a second one for the ECU, which also controls the fans.

Yes you are right. After starting the engine with the coolant temperature sensor on the radiator disconnected the gauge started to rise indicating that it doesn’t have anything to do with the temperature gauge. Since my voltmeter reads resistance from the relays but not from the old or new coolant temperature sensor I’m wondering if the new sensor is already faulty. I have ordered another one and will test before I but to see if that is the case. If not I will bypass and install a couple switches for the fans
Many thanks for your help
Very much appreciated

 

[Communicator]

@Skindiga

Hi Stuart,
I am sorry but in this world of sensors and engine control units (ECU), you do not seem to be understandint the simple thermostatic switch , aka thermostat, which is simply a switch that operates at a defined temperature. At ambient temperature both contscts on your radiator mounted thermostatic switch will be open. When connecting your multimeter across any pair of contacts the Ohms reading should approach infinity, an open circuit. If the thermostatic switch is heated to above normal operating temperature of the engine, the first thermostatic switch contact will close and operate the relay for the first fan. If the engine temperature continues to rise the second contact should close, and start the second fan in a similar fashion. A further rise in engine temperature may illuminate a red warning light. This ultimate warning light is operated by a thermostatic switch inthe same housing as the gauge sensor. See LHS section, 21, only of attached diagram. I have no faith in section 22, which only shows one fan, and no relays.

I hope that the above helps.

I have used the term thermostatic switch to differentiate from the temperature operated engine cooling circuit valve, which normally regulates engine temperature, and is usually referred to as the thermostat.

 

[Skindiga]

@Skindiga

Hi Stuart,
I am sorry but in this world of sensors and engine control units (ECU), you do not seem to be understandint the simple thermostatic switch , aka thermostat, which is simply a switch that operates at a defined temperature. At ambient temperature both contscts on your radiator mounted thermostatic switch will be open. When connecting your multimeter across any pair of contacts the Ohms reading should approach infinity, an open circuit. If the thermostatic switch is heated to above normal operating temperature of the engine, the first thermostatic switch contact will close and operate the relay for the first fan. If the engine temperature continues to rise the second contact should close, and start the second fan in a similar fashion. A further rise in engine temperature may illuminate a red warning light. This ultimate warning light is operated by a thermostatic switch inthe same housing as the gauge sensor. See LHS section, 21, only of attached diagram. I have no faith in section 22, which only shows one fan, and no relays.

I hope that the above helps.

I have used the term thermostatic switch to differentiate from the temperature operated engine cooling circuit valve, which normally regulates engine temperature, and is usually referred to as the thermostat.

@Skindiga

Hi Stuart,
I am sorry but in this world of sensors and engine control units (ECU), you do not seem to be understandint the simple thermostatic switch , aka thermostat, which is simply a switch that operates at a defined temperature. At ambient temperature both contscts on your radiator mounted thermostatic switch will be open. When connecting your multimeter across any pair of contacts the Ohms reading should approach infinity, an open circuit. If the thermostatic switch is heated to above normal operating temperature of the engine, the first thermostatic switch contact will close and operate the relay for the first fan. If the engine temperature continues to rise the second contact should close, and start the second fan in a similar fashion. A further rise in engine temperature may illuminate a red warning light. This ultimate warning light is operated by a thermostatic switch inthe same housing as the gauge sensor. See LHS section, 21, only of attached diagram. I have no faith in section 22, which only shows one fan, and no relays.

I hope that the above helps.

I have used the term thermostatic switch to differentiate from the temperature operated engine cooling circuit valve, which normally regulates engine temperature, and is usually referred to as the thermostat.

ok, your absolutely right, when it comes to modern electronics I’m pretty lost. I’m used to anything with some good old carburettors tbh. I’ve been checking for resistance when really I should be checking for continuity when hot. I will test and replace the thermostatic switch with the new one I have tomorrow and fingers crossed.
After the info you have given me I’m pretty sure it should the source of my problem. But I will have to try and see.
Will let you know the outcome
Again many thanks

 

[Skindiga]

ok, your absolutely right, when it comes to modern electronics I’m pretty lost. I’m used to anything with some good old carburettors tbh. I’ve been checking for resistance when really I should be checking for continuity when hot. I will test and replace the thermostatic switch with the new one I have tomorrow and fingers crossed.
After the info you have given me I’m pretty sure it should the source of my problem. But I will have to try and see.
Will let you know the outcome
Again many thanks

Ok so fitted new thermostatic switch to radiator this morning.
Went for run in the van and when I got back the temperature gauge was reading one mark above half way.
Disconnected the terminal with the engine running and checked for continuity between all the terminals on the switch.
None of them showing continuity.
However unlikely it may be it would appear that the new switch is not working.
The engine was definitely hot enough and when I touch the terminals or my volt meter it beebs so that is the only conclusion I can come to.
Unless you guys have any input?
Many thanks

 

[Communicator]

Ok so fitted new thermostatic switch to radiator this morning.
Went for run in the van and when I got back the temperature gauge was reading one mark above half way.
Disconnected the terminal with the engine running and checked for continuity between all the terminals on the switch.
None of them showing continuity.
However unlikely it may be it would appear that the new switch is not working.
The engine was definitely hot enough and when I touch the terminals or my volt meter it beebs so that is the only conclusion I can come to.
Unless you guys have any input?
Many thanks

Do not expect the fan to operate at normal operating temperature! When driving with air flowing through the radiator, the engine temperature is unlikely to rise to fan oprating temperature. If you can park somewhere where running the engine whlile stationary is not obfectional. Stop with the engine ticking over or rev slightly eventually you will see the indicated temperature start to rise. Fan should eventually start., probably about the 90C mark

See this earlier thread relating to a similar engine.

 

[Skindiga]

Do not expect the fan to operate at normal operating temperature! When driving with air flowing through the radiator, the engine temperature is unlikely to rise to fan oprating temperature. If you can park somewhere where running the engine whlile stationary is not obfectional. Stop with the engine ticking over or rev slightly eventually you will see the indicated temperature start to rise. Fan should eventually start., probably about the 90C mark

See this earlier thread relating to a similar engine.

Thanks for your reply. I engine was definitely hot enough that the fans should be kicking in. I’m in Spain and it’s 30 degrees so going up hills the 1.9TD working hard. Will keep trying any keep everyone updated.
Many thanks

 

[OldEngineer]

I'm pretty sure the switching is on the Earth side and it seems you have a poor Earth. If I'm right, Live will be permanent so you just have to trace the Earth path.

 

[OldEngineer]

I am wrong.
But there is good information in this post where the owner found this problem...

I dug deeper into the issue. Turns out the wire in the loom between B001 connector 28 and ECU pin 69 had snapped. Wasn't easy to find but after connecting two said pins between a multimeter and squeezing the cable loom the problem became obvious. Soldered the wire back together and I'm hopeful that will be the end of it...

Engine cooling fan trouble - the right behaviour? | FIAT Ducato

Vehicle: X250 3.0 2007 (Citroen version) I'm troubleshooting a high speed fan error: when using the A/C in heavy traffic/hot weather the ECU threw a code on the high speed fan. I hooked up MES to actuate the right relays and after some fiddling relay T06 came back alive and fan N012 kicked back...

www.fiatforum.com

 

[jackwhoo]

The thermo switch type does not switch fans on until very very hot ie near or even above 100 degrees c. Very high up on vehicle temp gauge.
If you have your old thermo switch check it switches on in a pan of boiling water.

 

[Skindiga]

The thermo switch type does not switch fans on until very very hot ie near or even above 100 degrees c. Very high up on vehicle temp gauge.
If you have your old thermo switch check it switches on in a pan of boiling water.

It’s stamped on the side of the switch.
One fan comes on from 83-87 and the other at 88-92 or something close to that. Can’t remember exactly but it’s in the 80-90 range. Never known a temperature gauge to get up to way above half without fans coming on. Definitely an issue there. I will test old switch in a pan tomorrow and update.
Many thanks guys

 

[Skindiga]

It’s stamped on the side of the switch.
One fan comes on from 83-87 and the other at 88-92 or something close to that. Can’t remember exactly but it’s in the 80-90 range. Never known a temperature gauge to get up to way above half without fans coming on. Definitely an issue there. I will test old switch in a pan tomorrow and update.
Many thanks guys

Tested old switch in a pan on the hob this morning and it is working. Not sure what temperature it was at as was in direct contact with bottom of the pan but it worked.
I’ve had this van nearly in the red on the temperature gauge you couldn’t even touch the radiator hoses they were so hot and the fans didn’t kick on so not sure what going on.
I bridged the terminals for the switch the fans come on also tested relays and continuity of the wiring so everything wiring/relay wise seems ok.
Going to fit a couple switch’s to the van tomorrow via the relay terminals.
We are heading to Morocco in a few months so probably wouldn’t hurt anyway to have a couple switches.
Not ideal but it will fix the problem.

 

[jackwhoo]

Manual switch is not a bad idea but don't wear out the fans by running them when not needed.

if the thermo switch is near the outlet of rad it will be cooler than the temp gauge sensor reading, so do not expect the fan to come on when the gauge reads.

Have you checked the thermostat opens at correct temp? Opens fully? Pan of water on hob and thermometer test.

Re:Morocco If you need to bring temp down quickly spraying the outside of rad with water works very well

 

[Skindiga]

Manual switch is not a bad idea but don't wear out the fans by running them when not needed.

if the thermo switch is near the outlet of rad it will be cooler than the temp gauge sensor reading, so do not expect the fan to come on when the gauge reads.

Have you checked the thermostat opens at correct temp? Opens fully? Pan of water on hob and thermometer test.

Re:Morocco If you need to bring temp down quickly spraying the outside of rad with water works very well

The thermo switch is near the bottom hose of the radiator i.e the cooler one so I did wander if the thermostat was not opening fully. Will have to test. Will update when I get the chance to test.
Thanks guys

 

[Skindiga]

Manual switch is not a bad idea but don't wear out the fans by running them when not needed.

if the thermo switch is near the outlet of rad it will be cooler than the temp gauge sensor reading, so do not expect the fan to come on when the gauge reads.

Have you checked the thermostat opens at correct temp? Opens fully? Pan of water on hob and thermometer test.

Re:Morocco If you need to bring temp down quickly spraying the outside of rad with water works very well

So tested thermostat works fine clearly been replaced before as there was gasket sealer in housing joint and it looks brand new
Was really hoping it was gona be faulty.
Switches it is I’m afraid
Thanks again for your help guys
Much appreciated