I haven't heard the cooling fan running on my 1.9D Felicia for ages, even when the temperature gauge  nears 110^oC. I tested the fan by bridging the terminals on the connector on the back of the radiator fan switch and it runs. There are 3 terminals and I bridged the live and the one next to it. I don't know what the third terminal's for.

Any ideas?

 

So today I fitted a new radiator fan switch, ran the engine up to full temperature and then let her idle so that the needle continued to climb. The fan still doesn't come on. I bottled out at 110^oC and turned on the heater to prevent a head gasket failure.

 

It probably needs a new thermostat as well. The needle hovers around 70^oC in normal driving. Would this have a bearing on the fan not operating when higher temperatures are attained?

 

Anyone come across this problem before on the diesel engine or anyone got any opinions?

the radiator fan has 2 stages.

that is why the thermal radiator switch has 3 pins (3=common positive, 2=low, 1=high).

 

check the 2 fuses and relay inside the additional relay and fuse holder for coolant fan.

 

I think too that you'll have to address the new thermostat issue.

on second thought, start by checking the connector of the radiator fan for corrosion.

from your description 1st stage of the fan is not working.

what resistance you get between pin 1 (black) and pin 2 (also black) of that connector?

Thanks Dohnjoe. I'll check the resistance tomorrow and get back to you with the results.

Hello Dohnjoe.

The wires on my car are red (live), black and blue. I measured the resistance between black and blue and got 74 ohms.

How does that sound?

sounds good.

that is the resistance in series with the fan motor for first stage low speed.

that makes me think at this:

is the temperature gauge indication reliable?

what if all is a combination of bad thermostat and temp. sensor faulty?

Possibly a partially stuck thermostat I'd say, it's not uncommon.

Thanks again Dohnjoe/Teflon Tom.

I've got a new thermostat, so I'll try changing that, as well as the coolant, at the weekend.

 

I too had started to wonder if the temperature gauge might be faulty. I'll see what happens after I change the thermostat and let you know.

I had a similar problem and it was broken / corroded wiring on mine. Can't remember if it was at the fan or the sensor now as it was a couple of years back but it was right at the connection - probably moisture getting inside the insulation started it.

 

Diesel is (as others have said above) a two speed fan. If my fan is running when I switch the car off it continues running then just before shutting down it goes to the 2nd speed. It rarely goes to 2nd speed on the road - only in traffic on a hot day.

Good point. I think the wiring on mine is ok. I bridged the terminals with a pair of pliers and the fan came on.

Whilst you are seeking a solution, why not consider fitting a switch across the terminals so that if you see a high temperature, you can manually switch the fan on . OH-and don't forget that you can also vent heat by running the heater on hot. But if heater EVER goes from hot to cold- STOP and investigate.

Indeed I was thinking of a 'manual over-ride'. It wouldn't be too difficult to do.

And, yes, if the heater suddenly goes cold it could be a sign that the coolant level's dropped significantly, which is never good!