I managed to get my fan test circuit installed yesterday. It was a public holiday over here and great weather so I took the opportunity to put everything together.
It's a very simple design, I bought a ready made relay delay circuit off ebay
which has a variable delay and can handle the current.
The idea being that when the ignition first comes on, the circuit turns the fan on for 3 seconds to let me know that it's still working, and also to give it a bit of exercise - ie stop it seizing up from lack of use during the colder months.
Here's how I wired it in -
I'm not proud to say that I wired the +ve feed to the circuit to the +ve feed for coil #2, I really should have ran a wire down to the fusebox as I really don't like interfering with the coils at all!
But this is really an initial test to see how it goes, so I will change it and wire it in properly once I'm happy that it works without any problems.
It has worked well so far, and I got stuck in traffic again today so at least I know that the fan operates as normal, although I did see the temp gauge get to 100°C for the first time ever, so that's concerning me a little.
I'll keep an eye on it and see how it goes, but I just bought the VW fan switch (with the lower activation temperature) as well and I'll put that in as soon as it arrives.