W123 engine fan

[Paulri]

Hi,

I'm suffering the common fault of the engine fan not kicking in on my petrol w123. I've replaced the thermostatic switch, still the fan isn't engaging.

To check the clutch, I've shorted the connection and the clutch kicks in and I'm in business, the fan engages.

I've ordered another thermostatic switch in the unlikely case the replacement was faulty. If this still doesn't work, is there something I'm missing. It's baffling me!

 

[alabbasi]

Consider converting to an electric fan and installing a radiator from a 560SEL which will fit.

 

[Paulri]

Thanks, I'll consider that if I can't get this sorted.

 

[Dodipops]

wiring fault to the switch?

 

[Paulri]

I don't think so, I'm shorting it from the switch contact point, earthing against the block which is engaging the fan clutch which I'd have thought means the circuit is okay. Unless it's a bad earth? I'll take a look at that tomorrow.

 

[grober]

I have a feeling the fan is always live and activated by shorting to earth via the thermo switch. If so are you getting a 12v supply? there may may be an additional inline fuse in the supply line?

 

[Paulri]

That sounds like it makes sense.

I'll have a look for a fuse tomorrow and check the power.

 

[Paulri]

I've checked the 12v supply, all seems good it's showing 11.4v.

Also checked the resistance of the 'new' thermostatic sensor, it isn't showing any sign of life even after heating it in a water bath. It does appear the replacement sensor was faulty.

Hopefully the second replacement will be here on Wednesday.

Fingers crossed it sorts the problem.

 

[Paulri]

Replacement sensor fitted and everything is back up and working.

Annoying that the original replacement didn’t do the trick but at least it’s finally sorted.