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Mpi Cooling Fan Not Working - Really Stuck And Need Some Desperate Help!


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#1 M700FGT

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Posted 16 June 2018 - 04:38 PM

Hi all,

 

Been having issues with the cooling of my 1997 Cooper MPI 1275.

 

Basically the fan is not turning on, so in traffic i overheat. Its clearly been an issue for a long time before i brought the car, as there was coolant all over the engine bay and the Coolant bottle was split (now replaced). Ive mainly been doing motorway driving, so never noticed it until i got stuck in London to Brighton traffic and overheated. 

 

So heres what i have done so far:

 

1. Checked the fuses, all ok.

2. Replaced cooling fan. I tested the old one with a 9v battery and it works, but it was looking rough and covered it oil and dirt.

3. Replaced radiator - Same thing, was working but had some damage and rust.

4. Was told to unclip the temp sensor in the thermostat area (This would turn the fan on) - made no difference.

5. A mechanic told me the above wouldn't work, but to put a split pin in the temp sensor wiring connector and it should turn the fan on - Didn't work. 

6. Checked the voltage on the temp sensor wiring loom - moves around a bit, but around 6v.

 

Apparently the thermostat was replaced before i bought the car, not that i think this would make any difference. 

 

What do i do next?

 

Any help would be greatly appreciated, as i desperately want him fixed and driving again! 


Edited by M700FGT, 16 June 2018 - 06:12 PM.


#2 Milton

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Posted 16 June 2018 - 05:04 PM

Have you tested the fan by connecting the wires together on the temp sensor. I have an spi which has the sensor in the bottom of the rad at the front, not sure where it is on the mpi.

If the fan runs with wires shorted then it is the sensor faulty or an air lock in the system.

#3 Steve220

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Posted 16 June 2018 - 05:19 PM

Typo - did you mean 'bought' the car?

My gut instinct says multi relay as you've tried the basics. Bridging the connector won't do much as it's your ecu that triggers the fan relay from the resistance reading of the sensor. If there's anyone nearby that has got an MPi that could swap there's over to check, that'd be my first port of call!

#4 M700FGT

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Posted 16 June 2018 - 06:26 PM

Have you tested the fan by connecting the wires together on the temp sensor. I have an spi which has the sensor in the bottom of the rad at the front, not sure where it is on the mpi.

If the fan runs with wires shorted then it is the sensor faulty or an air lock in the system.

 

That was number 5 - bridge with a split pin. It didn't work. 



#5 Carlos W

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Posted 16 June 2018 - 06:32 PM

Is there a relay for the fan?

#6 M700FGT

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Posted 16 June 2018 - 06:41 PM

Typo - did you mean 'bought' the car?

My gut instinct says multi relay as you've tried the basics. Bridging the connector won't do much as it's your ecu that triggers the fan relay from the resistance reading of the sensor. If there's anyone nearby that has got an MPi that could swap there's over to check, that'd be my first port of call!No I don't have access 

No I don't have access to another MPI mini, although if its just a relay they are only a few pounds on ebay. I don't know if there is a way to test a relay. 



#7 M700FGT

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Posted 16 June 2018 - 06:50 PM

Mini Spares list this: Relay for horn, front spotlamps, fogs, starter indicators, alarm, cooling fan, burlar alarm and oxygen sensor - The relays for the electrics appeared from about 1990 on and all single point injection cars and SOME are colour coded for ease-40 amp with 4 spade terminals.

 

Apart from the fan, all other systems are working. Could a relay fail on just one thing? 



#8 Carlos W

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Posted 16 June 2018 - 06:57 PM

http://www.theminifo...elay-locations/

#9 Carlos W

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Posted 16 June 2018 - 07:01 PM

Mini Spares list this: Relay for horn, front spotlamps, fogs, starter indicators, alarm, cooling fan, burlar alarm and oxygen sensor - The relays for the electrics appeared from about 1990 on and all single point injection cars and SOME are colour coded for ease-40 amp with 4 spade terminals.[/size]
 
Apart from the fan, all other systems are working. Could a relay fail on just one thing?


The relay for all those systems is the same type of relay but one relay doesn’t run all of those things

#10 M700FGT

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Posted 16 June 2018 - 07:03 PM

Thanks Carlos, thats perfect



#11 M700FGT

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Posted 16 June 2018 - 07:05 PM

 

Mini Spares list this: Relay for horn, front spotlamps, fogs, starter indicators, alarm, cooling fan, burlar alarm and oxygen sensor - The relays for the electrics appeared from about 1990 on and all single point injection cars and SOME are colour coded for ease-40 amp with 4 spade terminals.[/size]
 
Apart from the fan, all other systems are working. Could a relay fail on just one thing?

The relay for all those systems is the same type of relay but one relay doesn’t run all of those things

 

Thank you again - I did wonder.

 

So could I swap relay from another system to test, maybe the horn



#12 Carlos W

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Posted 16 June 2018 - 07:06 PM

http://www.theminifo...elay-locations/

Thanks Carlos, thats perfect

Where in kent are you?

Wired by Wilson can probably help?

#13 M700FGT

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Posted 16 June 2018 - 07:08 PM

 

 

http://www.theminifo...elay-locations/

Thanks Carlos, thats perfect

Where in kent are you?

Wired by Wilson can probably help?

 

Edenbridge - 15 mins west of Sevenoaks 



#14 Milton

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Posted 16 June 2018 - 07:14 PM

Have you tested the fan by connecting the wires together on the temp sensor. I have an spi which has the sensor in the bottom of the rad at the front, not sure where it is on the mpi.

If the fan runs with wires shorted then it is the sensor faulty or an air lock in the system.

 
That was number 5 - bridge with a split pin. It didn't work.

Haynes manual section 12.43 diagram 25 shows the wiring diagram for all injection models. There are two fuses to check numbered 93 and 94. 93 supplies 12v to the coil ofthe relay. The other side of the coil goes to the temperature switch then to earth. 94 supplies the relay switch contact. When the relay is energised by the temperature switch closing the contacts on the relay close and provide a supply to the fan motor.

#15 Carlos W

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Posted 16 June 2018 - 07:19 PM

http://www.theminifo...elay-locations/

Thanks Carlos, thats perfect

Where in kent are you?

Wired by Wilson can probably help?
Edenbridge - 15 mins west of Sevenoaks

He’s in Tunbridge Wells if you get completely stuck




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