Fan still not coming on.

[tilbo]

Hi, got a 93 1.8 190e had a problem with the fan not cutting in when required so bridged the connection so the fan was running all the time, fitted new temp sensor (located behind thermostat housing fiddly job) but fan still not coming on has anybody else had this problem is there something else i should be replacing ?thanks in anticipation.

 

[Sp!ke]

are you talking about the viscous coupling or an electric fan?

 

[Druk]

Has this engine got the electro-static fan coupling? and you're saying it's not working without bridging out the temp switch? The engine has to get really hot before this activates. To test the switch immerse it in a pan with a thermometer and bring the water up to the boil noting (with a meter or test lamp) when the switch closes.

 

[tilbo]

Fan still not working

Hi again, yes it has an electromagnetic cooling fan as i have said i have changed the temperature- sensitive switch located in the cylinder head, i realise the temp has to be high for the fan to operate but i think steam emitting & coolant coming out of the expansion tank counts as high temp!! The fan does not come on at all , can i put the fan on a separate switch from within the car rather than bridging it so it is running all the time?

 

[Druk]

If bridging out the sensor terminals makes the fan operate then it can only be the sensor at fault. Even a new one can be faulty although it does seem an amazing coincidence if it is. There are a couple of sensors in that region of the head. You're not mixing them up by any chance? For instance...dealer fitted aircon had an extra sensor fitted to operate the condenser fan in combination with the OEM fan cos of overheating problems caused by reduced airflow. To fit a manual switch just extend the two sensor wires into the cabin and fit a simple toggle switch. You could have this wired in parallel and you would then have the option of manual or auto operation.

 

[tilbo]

Best way forward with fan fault.

Hi again, no air con fitted so have no doubts as to sensor , could be another faulty one but i do not really want remove it, i think manual switch is possibly the easiest way forward at this stage.

 

[aircondoc]

Could this be a broken wire perhaps? So no circuit is made to the fan even if the sensor works?

 

[grober]

What do you mean bridged connection exactly? IIRC there are 2 wiring arrangements for the electromagnetic fan one is simple the electromagnetic clutch is supplied with 12v and is activated= earthed via the thermoswitch on the cylinder head. In some setups a relay is involved where the the thermo switch is used to activate the relay which supplies power to the clutch. Might be useful to check out presence of supply voltages + thermo switch continuity with a digital voltmeter to see which wiring system you have?