MG Car Repair: cooling fan problem, inline fuse, fuse holder

Question
Barrie,

Again I'm at a dead end!  I checked all the black lines had already cheked the connectors for the fans cleaned as suggested; have just been under the hood cleaned all black connections even the two heavy gauge that are strapped to the fender well with a wiring harness.
Is there a possible relay switch that may be have faulted?
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The first switch on the fuse side is black labeled LUCAS the numbers 87,86 85   30/51  are on the top of this it has a brown, black and a brown & tan wirea(s) hooked to it!
Thed next switch I see is a small one attached to the fuse box that has 2 wires one green one tan/brown the green wire indicates (A) designation the other has a v indicator.  May I ask what these are for??
Could either of these be my problem?

again thanks for your expertise & speedy responses

pete

Answer
Hi Pete.  It could be the fuse.   The small tubular item with Green wire plus Brown wire is an inline fuse holder for the fan(s).  It twists open to reveal a glass fuse inside.

The black tubular box with 4 wires comning from it is the ignition relay. I do not like the way it is wired as standard, because each fan takes up to 8 amps, which is a huge load.  Take a wire directly from the bottom fuse (brown side) and connect it to the Green wire coming out of the separate line fuse for the fan(s).  Jumper the two wires going into the thermostatic switch in the radiator header tank, and the fans should immediately burst into life, even with the ignition off.  If the fans work, it is the relay that is at fault.  I have fitted an extra relay to my MGB (V8) just for the fans.