radiator fan voltage?

[clartsonly]

my radiator fan does not turn..

I assumed it was faulty but checked the voltage yesterday and when I bypass the termoswitch I only get 2 volts?

If I remove the 30Amp fuse I get 0 volts, which is expected and if I remove the relay numbered 24 (radiator fan relay in slot number 5) I only get 1Volt

could this be a faulty relay, bad earth or incorrect wiring?

I am at a loss I am sure this should be 12 volts?

[edoh]

I would assume 12 volts too ...
how are you checking ? - w meter? test lamp? - connected how? with switch on/off? - i assumed - any part that 12v battery feeds - should read the same as the battery - 12ish volts?

a tony tech type will be along soon to tell us more i hoipe!

[airhead]

Yes it should be 12v or a little more really. Its either a faulty wire or relay.

[edoh]

how would you test with a multi meter set to 20volts - between which points? would the ignition be on? any way of checking relay with the meter?

[Mocki]

you shouldnt need the ignition on, iirc, and you should have 12vdc at the thermo switch, and beyond
take your readings from van body and pos, and then from neg wire to pos

[Mocki]

you shouldnt need the ignition on, iirc, and you should have 12vdc at the thermo switch, and beyond
take your readings from van body and pos, and then from neg wire to pos

[clartsonly]

thanks for all the replies.

Some extra information

it is a single speed fan, and I am informed that the relay is not used in the case of a single speed fan. although the reading is only 1 volt climbing to 2 volts without the relay connected, and 2 volts climbing to 2.2 volts with the relay connected (so I am a bit confused there.

The results are the same whether the ignition is on or off.

I am measuring on the fans connector and bypassing the thermoswitch with solder, with an LCD multimeter set to 20 volts, if I use the multimeter on the battery terminals is reads about 12.5 V engine off and 13.5 V engine running. so I know the multimeter is working okay.

if I connect the otherway around on the fan connector I get -2volts.

I have not checked fan connector + to body, it says in the haynes manual that if you short the thermoswitch on the bodywork the fuse will blow. I know this is the fan connector, will that blow the fuse too?

If I am getting 2 volts at the fan, does that mean that I will get 2 volts across the fuse too, or should the fuse still have 12 volts if it is a wiring fault?

I will try and check behind the fuse box tonight to see if any wires are not connected very well.

[tonytech]

Is the fan still connected while taking these readings?

Shorting any live wireing to bodywork(-ve) will blow a fuse (if there is one, bloody big spark if there isnt). keep bare ends away from bare metal.
If you disconect the fan and get a 12V reading on the terminals then you have a poor connection somewhere, The most likely trouble is a bad earth.
I'm not sure about the relay.

T

[edoh]

THIS IS FROM ANOTHER SITE -
R U SURE NO RELAY IN YR SYSTEM?

My problem (no power to fan at all) was caused by a poor connection to ground from the relay under the dash. However, fixing the connection did not immediately solve the problem. I had to remove the relay and replace it again (pull it out and push it back again) before the system functioned. I assume this is because the relay gets its knickers in a twist without the ground connection, and needs to be fully disconnected before it can untangle them. (I actually purposefully removed the earth again to test the theory and is seems correct.)

So when troubleshooting this problem it's a good idea to know that whilst all connections may seem good the relay may need removing and re-inserting before the fan will work.

OFFERED UP IN GOOD FAITH -

[clartsonly]

okay thanks,

I can test the relay works by putting 12 volts across the 85 /86 pins and should hear a click.

I can check the fuse voltage by removing the fuse and will carefully remove the fuse and relay box and check the wiring at the back.

allowing for light and multimeter availability.

[clartsonly]

grrrrrr

relay is not joined up so on a single speed fan it is not used. I managed to push a bit of solder in each fuse bit to check the voltage this was 9 volts rising so I reckon if I got a good connection it would be twelve volts.

pulled out fuse box had a look and retested at radiator fan connector was not 11.57 volts connected back up and again and the fan still doesn't work!!!

I will now try and connect the battery straight to the fan and if it doesn't work assume it is broken.

does anyone know whether I can get a replacement fan motor from somewhere? GSF and JK dont seem to sell them.
I am going to have to hacksaw off the spare wheel retainer bars to drop the radiator too.

[Mocki]

whoa! put your hands where we can see them and drop the hacksaw!

you can take the spare wheel retainers out without a saw! they "hook" in the rear end after you take the front end off.....

take a know good ( and more than 10amp ) feed of pos and neg 12vdc to the fan motor, see if it fans!

If that works, run a new replacement pos feed through from the fuse box, check again........ elimination, dear boy eleimination...... work backwards!

once you have the fan working direct, you can establish if the thermoswitch does, or doesnt switch.

[clartsonly]

I hear you.

If the radiator fan does not turn from a feed directly from the battery ( which I will try first at the weekend then the fan itself needs replacing doesnt it?

in which case
The retainer bars are supposed to come out where they are part of the hinges for the spare wheel shelfy thing, I have broken off the hairpin clips and spent about an hour trying to hammer them out of the hinges without moving the rusty bars 1mm. I suppose I could try and get a slide hammer from somewhere.

but
If with a source directly from the battery the radiator fan does actually turn, does this mean that even though I have 12 volts on a multimeter at the fan end of the wire if I have bypassed the thermoswitch, the fan is still not getting enough juice because of a weak wire?

I cannot measure the amps required by the fan with a different setting on the multimeter can I? maybe by joining the fan and using the multimeter set to amps bypassing the thermo switch? if I do this currently I get 12 volts..

[Grun]

Try this,
1. With the fuse in place, battery connected, both wires diconnected from the Thermoswitch And not bridged.

2. Now the Red and white coded wire is the one from the fuse and with the red probe of your multimeter on this and the black probe on a known good earth, you should read battery voltage. (20volt range on multimeter)

3. Check if you can whether the fan blades can be turned with your fingers or something. In other words are the bearings free.

4. Is the wiring from the fan to earth OK.

5. You could check with your multimeter on Ohms between the other (Black/Red) wire at the thermoswitch to earth and the reading (I think) should be about 1 Ohm or less. I am no electrician but there will not be a high resistance. High resistance would indicate stuck brushes, burned out windings or a bad earth.
As Mocki says, do things in stages and eliminate each possiblity in turn.


Mike

[clartsonly]

3. Check if you can whether the fan blades can be turned with your fingers or something. In other words are the bearings free.

fan spins freely

4. Is the wiring from the fan to earth OK.

there is one socket on the back of the fan with the 2 pin jack plug, there is no additional earth cable, I thought this was a "closed circuit" which is why I can read 12 volts anywhere on the circuit when the thermoswitch is bridged. should the fan be earthed seperately?

I will try the other tests when there is daylight to use especially around the earthing issues (what is a known good earth, how can I tell a good earth point from a bad one?)