Rad Fans Wont Turn Off Now!

[edbar 6]

Well after advice of how to trouble shoot my fans on the 309 not working i worked my way through the list. the wiring of the rad was a state so rewired the fans (bodged twin fan conversion by previous owner), New fuse, then put a piece of wire between the two terminals in the thermoswith plug and they worked. So i assumed it was the thermoswitch itself, bought a new one and fitted it, still no fans (engine up to temp), so thought must be the connector block, cut that off and put spade connecter's on, then they worked. But they kept going even though the temp had dropped to about a quater on the gauge, the thermo switch was so hot it was starting to smell and melt. Have no idea what is going on as i wired it as the original connecter block was. Also found this cylinder connected to the fan loom (or seems to be ), disconnected it and the fans stopped, connected they ran. The pics show how i've wired the thermoswitch and the cylinder in question. Think im going to just fit a manual switch inside the car tommorow as i need this working to run the car. Any advice is appreciated, and excuse me if its a stupid post but i have no manuals for the car.

 

Cylinder thingy.

 

Thermo switch wiring.

[welshpug 1,657]

sounds like you've wired them up wrong so that the low speed has a permanent live feed, which explains why they stopped when you disconnected the resistor, sort that issue and you wont need to bodge a switch in

[edbar 6]

O.k thought it might be something like that, but i did wire it as it originally was, any ideas why that would still be? If i disconnected one of the connecters i.e low or high speed side it still ran. Sorry if im being stupid.

[DrSarty 90 1 Cars]

sounds like you've wired them up wrong so that the low speed has a permanent live feed, which explains why they stopped when you disconnected the resistor, sort that issue and you wont need to bodge a switch in

 

Totally. You have something wrong.

 

It's such an incredibly simple circuit and 99% of cars run fine without an extra dash switch. The standard circuit usually fails through a failed thermoswitch, failed resistor or damaged (aged) wiring.

 

As WP says (and be careful as these are high current, permanently live wires), reorder the wires on the thermoswitch (in the rad) and unless you've buggered the switch it should work just fine.

 

If you had to, you could always just bridge the wires to the resistor (your cylinder thing, i.e cutting it out) such that the fan only ever runs full tilt. But my 2.2 even on the EuroTrip only ever used low speed fan.

 

A dash switch is avoiding the issue.

[edbar 6]

If the resistor was buggered then would that make them stay on? And the idea of the dash switch was to avoid the issue.

[welshpug 1,657]

no, if the resistor was buggered you'd more than likely have no low speed.

 

 

 

I have spotted your error upon checking my car's wiring, the red and blue wires should be on separate pins, red is the permanent live, blue is the wire to the resistor, split those wires to separate pins and you should be sorted.

 

looking at the back of my 3 pin plug, the central top pin is red, left is blue for low speed via the resistor, right is white which feeds direct.

[edbar 6]

Thanks welshpug, what are the other wires for? Mine has two per pin?

[welshpug 1,657]

they are for a diagnostic plug to test the functioning of the cooling fan system.

 

they should match, i.e one thick red one thin red, one thick blue one thin blue and one thick white one thin white, thats based on the colours of my car, though they are fairly consistent across the years.

[edbar 6]

Thanks for your help, not a clue when it comes to wiring! So at worst i can forget them and leave them out the connectors?

[CosKev 16]

Thanks for your help, not a clue when it comes to wiring! So at worst i can forget them and leave them out the connectors?

 

Yeah if you want to bin the diagnostic plug and wiring

[welshpug 1,657]

finally got my phone to connect