Engine Radiator fan doesn't turn on

[ducksgoquack]

With the lovely hot weather we've been enjoying recently, I've very quickly noticed my air conditioning doesn't work when I'm in stop-start traffic. When I looked into it, I noticed the fan in-front of the radiator of my 1.6 Tdci 2006 Fusion isn't running, even after a long drive when I park after the coolant temp gets to around halfway on the gauge.

Troubleshooting

1. I checked the fuses behind the glove box, and none of them are broken. I'm not entirely convinced which fuse might be for the radiator fan but I checked a load of them (one with a fan icon, a few heater ones, the engine one, etc.) - no blown fuses. If anyone can confirm which fuse-code is for the fan I'd appreciate it.
2. Under the bonnet, the fan has two cables running to it. Closer to the top is was looks like a resistor of some sort. I checked it with my multimeter and it shows electrical continuity with 1ohm-ish of resistance. The second cable, hooked to the centre of the fan doesn't have a voltage across it when the engine is running. I'd expect this to have 14v across it to drive the fan, right?
3. Thinking there's no voltage going to the fan, and pretty sure there's no blown fuses behind the glovebox, I thought I'd look at the relays. From some reading online, my Fusion has air-conditioning so there are apparently two relays. One is behind the glovebox (a grey relay), and a second is behind the battery (a grey relay). I tested the voltage across the low-current terminals of the relay socket, and got around 10V, and the high-current terminals returned 0. I checked the other relay sockets, and they returned 10V on the low-current terminal, and 14V across the high-voltage terminals. This is this same on the relay behind the glovebox, and the one behind the battery.
4. When unplugged, the relays have continuity with my multimeter across their low-current terminals (and not across their high-current terminals as you'd expect, I suppose)

This troubleshooting says to me that the fan motor isn't getting a current, because the wire for it isn't live. If it's not live, then the fuse must be popped, but I've no evidence of that. 

Why isn't my fan getting a voltage?!

What would you guys suggest I look at next?

[iantt]

Bothell the relays are fed by 40amp fuse (FD)at battery junction box.you should have battery voltage at both relays.

So check the relay next to battery,  check  pin 3 for battery voltage. If you have battery voltage, bridge the pin 3 to pin 5 opposite (briefly) and high speed fan should operate. 

[ducksgoquack]

Sorry if this a stupid question, but which battery junction box are you referring to as having the 40A fuse?

Directly behind the battery is a small cubic box containing the three relays I've poked around with. Where are the fuses?

[iantt]

Fuses will be very near the battery. They are large fuses bolted in. Follow the main positive wires from battery and you will find them . Probably hidden by a plastic cover

Have you got 12 v at pin 3 location with relay out? 

 

[ducksgoquack]

With the relay out, pin 3 is 0V

I was able to test the 40A fuse in the engine bay fuse box (located in the most awkward place I've ever come across) - and it's blown. It's behind the battery, underneath the relay pod with about 0.5cm of slack to crack open.

Attached is the photo of the general location of the fuse box for anyone who finds this post on Google. You need to remove the positive battery terminal, remove the pair of rubber tubes running across the relay box, remove the battery restraining bar (one of my bolts was stripped - fantastic 😅), wriggle the relay box to the side, then use a flat-head screwdriver to pop the plastic fuse box open.

Second photo is inside the fuse box. The green fuse is the 40A one, which is fails a continuity test with my multimeter. The yellow one to the right is 60A and is fine.

There's no chance of swapping the 40A fuse out in its current situation, so I think I'll need to take the battery out to get the space.

 

It's all a bit unremarkable really, getting a fuse changed. At least it looks like I've actually found the culprit for the radiator fan not working... 

[iantt]

at least we are getting there. now you will need to find out why its blown. 

[iantt]

the relays had issues with overheating and jamming on, so that could be a possibility or the fan at fault. does the fan turn freely? 

[ducksgoquack]

The fan moves if you give it a prod. I wanted to put 12v across it to see if the motor would spin, but the pins for the fan are in such an awkward position it's not really possible.

I have a few theories as to when this started. One is when I went through an automatic car wash with the A/C and blowers on, but the engine off. When I came to pull off at the end, the engine wouldn't turn over and I had to bump-start it. Perhaps the bump start put a current surge through some of the accessories and popped the fuse.

 

[ducksgoquack]

40A fuse replaced (you have to take the battery out to get decent access to the fuse box) and the fan worked for about a day before popping again when idling in a car park.

I'm going to guess that the fan is drawing too much current when operating, causing the fuse to pop (as opposed to wiring shorting out, which I'd expect to happen instantly rather than a day later).

So, that leaves me with either squirt a bit of grease into the motor bearing to see if that helps it along (sensible?), and swap the fan out. Sound like a plan?