Removed Battery Surround - Now Overheating

So I kind of solved my own problem...I think.

Hit some 45 minute traffic jam this morning on the way to work. Ambient temp was about 12C and the car began to warn of over heating when reaching the 4th line. Bit odd. Usually it sits bang in the middle of 2 and 3 but going up to 3 when in traffic or going for it. I managed to keep turning the car off and rolling it to save it ever getting over more than the 4th line.

After reading up possible causes in my lunch break at work I found this connector loose beneath the fuse. Must of happened when I had the surround out last time so the radiator fan was no longer coming on.

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So I think that fixed it. However I have since been able to try and get the radiator fan to come on in idle to check if it is all fixed. I left the car for 15 minutes after driving home and it wouldn't got above the 3rd line - good - but no radiator fan coming on.

Any thoughts? Is this normal? I just don't want to get screwed in traffic again!