Pos or Neg

[Steve T]

Hi all

Could someone kindly inform if the rad cooling fan is switched Negative or Positive as it will continue to run with ignition off for cooling when we get hot weather, its only happened a couple of times on mine, need to know for a wire connection and switch position on the alarm so it does not set off a false alarm. 1.9 DG 1984
I am in the process of fitting an alarm for when my other security devices are not in use so I have another choice of method for theft deterrent.

Thanks

Steve

[Hacksawbob]

The fan will continue to run when the ignition is turned off by design, You can test the plug on the bottom of the rad behind lower grill on the right hand side. I am pretty sure the centre of the three pins is positive and the thremostat either has no contact (cold) High or low fan to one or other of the outers temperature dependant.
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[Steve T]

Thanks for that, so you think it is Positive switched,
I knew it was meant to run with ignition off, it needs some high temps to get it to run but as most know a temperature can creep higher when not circulating on some vehicles after a trip, especially if stuck in traffic.

[ghost123uk]

Easy enough to check with a simple multi meter

[Hacksawbob]

Yes, pretty sure. test centre pin to earth
continuity = negative switch
12V = switched live

Have the high speed fan come on when movement detected, that would scare the cr@p out of them !