My 73 2+2 had a functional radiator fan that has suddenly stopped coming on - i get normal temp reading in the water indicator that then moves towards high at slow speeds and idling. Today, I had a full on coolant spill from overflow tube after a short drive and returning home.
I have looked at the posts on the wiring and as far as I can tell, there are no wires that have come off the relay. I presume the wiring is fine because this used to work before.
Would appreciate a little detail in your suggestion since I have not worked on electrical wiring issues with cars before.
First question is whether the fuse is OK. Even if it looks visually ok, check that there’s power at the relay. Next, check that the fan switch works. It’s located on the lower radiator hose. Undo the plug and short the harness contacts (key on). The fans should come on. If not, it’s more than likely the relay. Lucas relays can usually be rebuilt by undoing the crimps on the case and dressing the points. Finally, it could be the fan motor itself. Undo the harness and test with a 12v source.
That C3 contact should have a ground wire, but that’s not causing this problem.
I checked the fuses and they look good. Would I test the relay with a multimeter for continuity? Which pins on the relay? Or would I test this by applying power From the battery using alligator clips ?
I located the fan switch on the lower radiator hose. I pulled out the two wires and when I connected them, I heard a clicking sound only when the ignition key was in off position. In the on position, nothing happened.
Incidentally, the horn is not working either.
Take the relay out, noting which wires went where. You will need to remove the radiator cowl to get to the relay. The pins on the bottom are labeled W1, W2, C1, C2, C3. Apply 12V across W1, W2. You should hear the click. Then, use a multimeter to test continuity across C1, C2. If you don’t hear the click, the relay is probably unsalvageable. If you do hear the click, but don’t have continuity, then the contacts are probably carbonized. In this case, straighten the crimps that hold the board to the can and pull them apart. Dress the contacts with a small file, and reassemble.When you put the relay back in, make very sure that the correct wires go to the correct pins.
The process for testing the horn relay is exactly the same. For Lucas relays, just remember that W is winding and C is contact, and you’ll be able to figure out any problem.
Did you physically pull the fuse out and look it over ? Years ago I was having intermittent fan problems as well as some others like the horn. Fuse was not blown but when I pulled it out an end cap was loose and I suppose not making contact at times. I do not know anything about Series 3 but on my '68 the fans and horn are on the same fuse.
David is on the right track!
If the fuse is not blown, it may be that the contact between the fuse and the clips is not good. If have often taken the fuse out and put it back in a few times and this removes unseen corrosion or finds a new contact point. The problem is the the tension of the metal clips that hold the fuse in place is lost over time… ie over 50 years!!
Dennis 69 OTS
I got spare fuses yesterday and will test this out today.
Michael - thanks so much for the detailed instructions and will follow up on this after testing the fuses. A quick question - can I use the car battery as the 12V power source to test the relays (after disconnecting the wires that go into each) and also can I just use 14 AWG wires with alligator clips from the battery and test the relay without removing it?
In other words, is removing it just for convenience to test better or was it based on other concerns like damaging it?
Lastly, how do I add an earth wiring since its missing from mine?
Thanks all as always and I am happy to report that I became a patron yesterday!
So I replaced the fuses even though all of them have good continuity upon testing and the metal piece is of course intact.
I have now tested the relay and exactly as Mike said, I do hear the click between W1 and W2 and there is continuity between C1 and C2.
As I noted earlier, when I connected the wires directly to each other, there was a click which corresponded to the other relay, as shown in the pictures.
How do I test the fan motor? Any other suggestions?
tried to start the fan on the left side (facing the car) with battery by connecting one of the black green wire i the picture to positive and the black wire in my hand to negative. Nothing happened. When I switched it, got a spark…I was under the impression it would just spin the other way but perhaps thats a silly mistake on my part.
Any follow up would be great!!
I am a novice but don’t want to give having tested a few things…
Some interesting progress: took the motor out and tested with 12v power - nothing happened. Then took the motor apart and cleaned the insides with rubbing alcohol to ensure the brushes were clean and voila- the fan worked.
In need to now put it back in and see if the car’s electrical system will power it, then on to the second fan and see if it’s a similar issue.
Can anyone let me know where the relay for the horn is?
Passenger side behind mudshield (panel behind tire) 2 Flathead screws on tire side - bracket and nuts inside. From side of car looking at battery it would be a bit forward and behind the AC dryer.
