Testing Fan

[TaffyTim 6]

Am I right in thinking if I take a wire straight from the positive terminal to any of these three pins then the Dan should fire up/fire up slow/do nothing?

[TaffyTim 6]

[Rock Lobster 28]

That's what cuts the fan in I think, one pin for high speed and one for low speed through a resistor.

 

I'm not an expert but if you jump across from the live on the plug rather than the switch, you should be able to run the fan in either speed. No need to go from the battery because I think there should already be power available for the fan to run. Isn't there a plug to test the fan on the fan loom somewhere?

 

I stand to be corrected!

[TaffyTim 6]

thats what i thought, so i took a feed from live to each of these pins (singularly) and the fan didnt kick in.

 

Does this prove the fan is dead or did i need the plug in when testing?

 

I couldnt see how i could test it otherwise as the plud going into it was looking pretty ropey.

[Rock Lobster 28]

You don't need it plugged in to test the fan, only to test the switch when the coolant gets up to temp, ie testing the switches normal operation.

 

If you want to test the fan, Jump from the central pin to one of the outer ones on the plug itself , not the switch and this should start the fan. Basically you will .be making the contact instead of the switch doing it.

 

So no need to have it plugged mate I think. Just need a piece of wire and you should be ok.

[TaffyTim 6]

OK I feel a bit of shame but after reading through tens of 'radiator fan test' and 'thermoswith' searches the penny has finally dropped that i need to be bridging the points inside the plug that connects to the above pictured thermoswitch and not sending a live feed to this switch (edit: oh like you just said )

 

When i was testing this earlier i was presuming that wires came out the other side of this switch but i now see they don't and the unit has a thermometer inside that then triggers the fan at certain temps. I think i understand correctly now that 1 pin is live going in and then after certain temps are reached the current is then directed back out to either the slow speed pin or the fast speed pin. Earth is found from the fan itself.

 

So by jabbing a wire that goes into the plug that connects to the above picture I'll be testing the actual fan as Im be directing the live feed directly to the fan taking this switch out of the equation.

 

The testing plug you mentioned Rock Lobster is not in my loom, it looks like its been snipped off.

Edited May 5, 2014 by TaffyTim

[Rock Lobster 28]

Yeah you got it! I have been going cross eyed so many times with the wiring mate I wouldn't worry about it!

[TaffyTim 6]

So, I have just been out to test it (not 1 tool was needed ) and I get no action on the fan no matter what combination of hole I bridge.
.

I take it this means that either:

 

1. I've lost the live feed to the plug.

2. I've lost the earth from the fan.

3. The fan is dead.

 

If I'm missing a possibility please say.

[Rock Lobster 28]

It's a fairk straight forward loom from what I can remember, so test esrths and feeds I guess as a start, I have foun a couple of broken wires around my car over the years too.

There are fuses in the shunt box that I think might be associated with the fan, I have a loom here in a box, so if I get 5 mins I'll take a look.

[welshpug 1,666]

Getting there!

 

A fourth suggestion is, the fan or feed osnt plugged in, so follow the wires and confirm that.

 

Also, a dead resistor would drop the lower speed, but it sounds like you have nothing at all.

 

 

 

check at the plug with your mm which pin is live, or infact you have live at all.

[TaffyTim 6]

I went out with my mutimeter tonight and have 12 v going to the thermoswitch plug.

 

I also have an earth coming away from the fan so i thought that this would mean that the fan itself must be dead so i ripped it out.

 

With it out i then connected it straight up to the battery and the bloody thing sprung to life.

 

So ive popped it back in and now am left thinking that its going to be the thermoswithch thats faultyI couldnt be anything else could it?

 

If i go to gsf tomorrow does anyone know what part number i need for the later type thermoswitch?

[welshpug 1,666]

http://forum.205gtidrivers.com/index.php?showtopic=150210&hl=intermotor&do=findComment&comment=1353624

[TaffyTim 6]

Thanks WP, I'll get one tomorrow. The only thing thats got me thinking now is why the fan didnt come on when i bridged the plug?

 

I dont remember seening the low fan speed resistor. Am i right in thinking this should be near the top of the radiator? There was a silver resistor by the nearside headlight but this should be something to do with the headlights isnt it?

 

If the resistor had been lost somewhere, I take it this wouldn't affect the high speed function of the fan?

[welshpug 1,666]

Indeed a missing resistor wouldnt affect high speed,

have you tried bridging the pins again now you have confirmed the fan works and you know which pin is the 12v feed?

 

 

Yes the resistor with the short fly lead under the headlamp is the dim-dip resistor.

Edited May 7, 2014 by welshpug

[TaffyTim 6]

Yeah as soon as i worked out which pin was live first thing i did was re bridge them and got nothing, checking i was getting a feed through my bit of wire too. So i was really surprised when the fan worked.

 

Maybe its a failure in the wiring between the thermoswitch plug and the connector to the fan loom

 

OK so high speed would still work, maybe it is there but i missed it. I'll have another look in the morning after i noticed the fan was working it was getting dark so i had a race against the sunset to get it all back together. Nature won and i finished off by mobile phone light!!

[TaffyTim 6]

New thermoswitch in and no change.

 

I if I want to test the writing from the thermoswitch plug to the fan wiring I take it I can get the car up to temp and this should switch the power to the fan, so I can test at the connection between the thermoswitch writing and the fan wiring?

[welshpug 1,666]

No need, just bridge the pins

[Rock Lobster 28]

You have established you have a reliable 12v feed to the thermoswitch and also that the fan operated when fed with an 12v supply. The earth from the fan has been tested and is good. And you have now replaced the thermoswitch for a new one so if it still doesnt work then I would suggest the wiring from the switch to the fan is suspect.

 

If I were you i would remove the loom and test all of the wires and find which one is at fault. Its only a basic and small loom so it will take a couple of minutes. Have a good look for corroded pins in connectors too as these have caused me a few issues in the past.

 

In theory if your wiring is fixed and good, plug it all back in apart from the thermo switch and bridge the pins on the switch plug, and at the very least the high speed should kick in. Low speed should work assuming the the resister still exists and hasn't been unplugged/removed.

 

I might have stated stuff you already know mate but there cant me much left to test so you will find the fault soon!

[TaffyTim 6]

No you speak sense, saves me fiddling under the bonnet. I'll whip it out when I get home

[MikeC 10]

You could rest it with a live from the battery direct through the plug to see does the fan work. Sounds like an earthing fault, and the earths in these areas are notoriously dodgy around the light panels. Maybe a fresh earth to the fan.

[TaffyTim 6]

Right, I've whipped it out and put it back in and i now have a working fan on both speeds when the plug is bridged

 

Bad news is that my temp gauge is still sky high in the dash (sensor is new so shouldn't be that).

 

I now think the rad is blocked as I've been for a drive with the temp gauge maxed out and come back and the rad is cold to the touch and the fan is off. The thermostat has been tested and works as it should, so it shouldn't be that either.

 

When my problems started my fan was working so it looks as if I've fought a fire but my main problem still exists.

 

Ive checked a few pipes to see if any are blocked and i found a blockage on the radiator side of the thermostat. It looked like metal has peeled off the inside of the removable metal part that the pipe secures to directly after the thermostat housing. When i found the blockage it definitely would have reduced the flow greatly so i thought i'd fixed it.

 

Ive been for another drive and the rad is still cold to the touch with gauge maxed and the fan was still not firing up (no surprise if rad has no heat)

 

Can i unblock the rad by flushing it out? It a relatively new rad so i cold do without losing it, if you go back to the pic above you can see its in good order externally.

[Miles 331 1 Cars]

Have you got any water flow? take the rad cap off when cold, start the engine and you should see a flow of water, If not your water pump could be goosed

[TaffyTim 6]

There is good flow going into the expansion tank.

[Rock Lobster 28]

Pop your thermostat housing and rad bottom hoses off and shove a hose pipe in to flush the rad and engine I doubt that the rad would be blocked though surely?

[TaffyTim 6]

Just of to do that now. To keep things tidy I've started a thread for this part of my headache. Thanks for your fan help guys.

 

Blockage thread: http://forum.205gtidrivers.com/index.php?showtopic=159110

Edited May 10, 2014 by TaffyTim