It would appear the radiator fan on my punto mk2 wouldn' come on at all, have checked the fuse under the bonnet without any luck.

Is it possible to rule out the fan or the wiring on the car before I start buyinng new parts? I have had a look round the forum and I gather the ECU sends a signal to the fan when it is required. Is there a temperature sensor on the block/head of the engine as part of this?

Thanks
David

I have a MK2b/3 but should be the same,have you checked the relay in the engine fusebox, without aircon(R6)with(R6&R7)also check earth from fan to chassis.The engine coolant temp sensor is located on the left-hand end of the inlet manifold identified by its green wiring connector,but if temp gauge is working/warning light then it is probably not at fault.Check connections on sensor/fan motor,you can check fan motor by putting 12volts through it,but be sure to disconnect the wiring loom plug from the fan motor before testing, if motor runs,= faulty relay/fuse or wiring loom.

Thanks for the reply.

Temp gauge on the dash is fine so as you say the engine coolant temp sensor should be fine. Also checked the fuse, didn't know how to check the relay though or tell whether it is faulty?

Good idea about putting 12volts through the fan motor, I assume through the connections towards the middles of the housing itself?

On the plastic fan housing three electrical connectors ae present:-
1. In the middle of the fan which appears to drive the motor?
2/3. Which as a pair go into the top of the fan housing, is this for the an speed resistor, and if so does it need checking?

Regards
David

If you have air con then u have a fan resister, hence 3 connectors,but you only need to connect live to connector the red wire goes to & the earth to the connector the black wire goes to, checking a relay is a bit harder as you have to get the car up to the temperature & listen to hear/feel with your finger on top the relay a click as the switch in the relay works, if no click then relay is probably at fault and substituting with a new one is the only answer.

Tested motor and all is fine, next step will be to remove temp sensor unit and see if the fan will engage when the sensor is dropped into a pan of hot water.

What does the large green resistor on the fan assembly do? Does the ECU take the temp of the radiator from this resistor, reason I ask is that it is rather close to the radiator.

Thanks
David

Hi, the sensor controls the fan, the resistor is to do with the relays.
The engine ECU supplies a set voltage to the sensor with other supplies & this controls the fan. Have you got the resistance readings useing a ohmmeter a thermometer and as you say hot water?.

I don't really understand what you are saying?

Sorry, forget about the readings blinding u with science, but I still dont think the sensor is at fault as you have not got a engine warning light on, if sensor goes faulty the ECU will automatically put this on but I did read that the sensor is about £13 to buy so if u r not sure, check for no broken wires in the loom between sensor & fan motor & dont rule out the relays remember 2 if you have aircon.

Thanks, the car does have aircon but the system has not been refilled for months after replacing the condenser unit.

I think I will be looking at get my hands on a new relay and then test while system again

What does the large green resistor on the fan assembly do? Is this a low speed fan sensor?

David

Hi,use search function on this forum enter(air con fan speed resistor)this will explain resistors function.Has the fan worked since the condenser was replaced?,do you suspect one of the relays.

inki said:

Sorry, forget about the readings blinding u with science, but I still dont think the sensor is at fault as you have not got a engine warning light on, if sensor goes faulty the ECU will automatically put this on but I did read that the sensor is about £13 to buy so if u r not sure, check for no broken wires in the loom between sensor & fan motor & dont rule out the relays remember 2 if you have aircon.

Click to expand...

Ah. So if sensor is screwed the ECU leaves fan on all the time?

Thats what happens with mine...

Resistor on fan:

Engine with AC has two speed radiator cooling fan. This is implemented with two relays and a resistor.

Speed 1 (low speed): ECU puts earth on coil of relay R6. Contact of R6 goes to fan motor via the resistor. The resistor limits the current hence speed is reduced.

Speed 2 (high speed): ECU puts earth on coil of relay R7. Contact of R7 goes straight to fan motor.

Other side of motor is earthed.

12V supply for both relay coils is via fuse F3 (30A) and ignition switch.
12V supply for contact of relay R6 is via fuse F6 (30A).
12V supply for contact of relay R7 is via fuse F7 (30A).


Car without AC only has relay R6 and fuse F6 (30A) supplying both coil and contact. No resistor. ECU puts earth on coil of relay R6, contact supplies fan motor.

red

psychocandy,

Failure of the coolant sensor is one possible cause for the fan to run all the time. There are other potential causes (e.g. welded contact on relay R6/R7) or wiring shorted out somewhere.

You could check the sensor using an ECU reader:

https://www.fiatforum.com/punto-gui...eset-ecu-airbag-errors-mk2-tenner-laptop.html

Or you could substitute the sensor for a good/new one.
Or you could first try checking/cleaning its contacts.

red

Hello, hope someone can help, the car is punto 2002 1.2 8v no air con. Now ive never herd my cooling fan working so i checked by powering it to batt and the motor is ok. I have checked fuse F06 and is not broken. I read that unpluging the temp sensor connecter will make the fan turn on, i did this and started engine but the fan doesn't come on. I replaced a relay, i replaced the red one for an exact code and colour match for the middle one on the right hand side of engine fuse box but still doesnt work.

Tell me in this forum thread the relay is labelled R6 as it is in my haynes book however in my book the fuse box diagram relays are unlabbeled, and then looking in the fuse box of care the relay ports are labeled as T codes such as T08 etc. how do i tell which relay is R6 please? thanks

T06 for R6. It is the red one nearest the back of the engine

This starts out as an oil thread but gets into the fan fairly soon. In my case the problem was a broken wire from the engine fusebox to the ecu.
https://www.fiatforum.com/punto-ii/428001-losing-oil.html

The rad fan is prone to sticking and if it does then the "on" signal is sometimes insufficient to get it running. Personally I would get a replacement second hand fan and shroud from a scrappy. No need to get dirty at a car brakes, an on-line parts reclamation store will see you right and it is economical. I have replaced mine with an identical model year part and the cure was immediate. I figure this is really important to sort out given how prone to overheating the punto engine is and the relative cost of that is huge compared with £25 for a replacement fan unit!

peaster2k said:

It would appear the radiator fan on my punto mk2 wouldn' come on at all, have checked the fuse under the bonnet without any luck.

Is it possible to rule out the fan or the wiring on the car before I start buyinng new parts? I have had a look round the forum and I gather the ECU sends a signal to the fan when it is required. Is there a temperature sensor on the block/head of the engine as part of this?

Thanks
David

Click to expand...

Check the fuse box wiring harness that runs over the battery
Check the grey wire. I had same problem and just found that the grey wire had a hole in and like green paste so cut it put it back together fan kicked in when temperature gauge got to half way try it mate worth a try

peaster2k said:

It would appear the radiator fan on my punto mk2 wouldn' come on at all, have checked the fuse under the bonnet without any luck.

Is it possible to rule out the fan or the wiring on the car before I start buyinng new parts? I have had a look round the forum and I gather the ECU sends a signal to the fan when it is required. Is there a temperature sensor on the block/head of the engine as part of this?

Thanks
David

Click to expand...

Did you solve the problem? if yes, please tell me how, because i have the same issue ión my Punto.

peaster2k said:

It would appear the radiator fan on my punto mk2 wouldn' come on at all, have checked the fuse under the bonnet without any luck.

Is it possible to rule out the fan or the wiring on the car before I start buyinng new parts? I have had a look round the forum and I gather the ECU sends a signal to the fan when it is required. Is there a temperature sensor on the block/head of the engine as part of this?

Thanks
David

Click to expand...

Did you solve the problem? if yes, please tell me how, because i have the same issue on my Punto.