Airflow Icon wiring

[davecooper]

A neighbour asked me if I could have a look at his Icon 12v bathroom fan over the weekend. It had been installed a few years ago with the "run on" timer module fitted. Previously it had run on for about 10 minutes after switching off the light but was now running indefinitely. He assumed that the timer module was at fault and ordered and fitted an identical replacement module. However, with this replacement, the fan now started to pulse. It would ramp up in speed then stop for a couple of seconds then ramp up again etc. I said that this could only be a fault in the new module so and we refitted the original for the time being, just without the run on operating.

When I got home I found the installation wiring diagram for the fan online and realised that this showed slightly different wiring to that in his fan. The output of the power supply has three wires and according to the wiring diagram these are: Grey - 0v, Brown - 12v and Black - 12v trigger. His was wired with Grey to the 12v trigger and Black to 0v. I went back and showed him this so we tried the two modules with the "correct" wiring configuration but in both cases, the fan did not run at all!
Can anyone shed any light on what might be going on? I cannot see how it can even be working with his current wiring unless perhaps there is a corresponding miswire between the RCD and the power supply.

This is the wiring diagram (page 5)

https://www.manualslib.com/manual/1433708/Airflow-Icon-15s.html

Thanks.

 

[morqthana]

You're absolutely sure he bought a 12V banana and not a 230V one?

 

[Murdochcat]

Did you take any photos before and after?

 

[Taylortwocities]

You're absolutely sure he bought a 12V banana and not a 230V one?

yes, my first thought too!

 

[davecooper]

He took a photo before removing the module and this backs up the fact that the wiring seems wrong. I assume the replacement is 12v as it has the same part number. I will have another look at the new one when they return from their hols.

 

[Taylortwocities]

I said that this could only be a fault in the new module

There are two items in play here. The module that goes in the fan, and the power supply.
You’ll need a multimeter to find out which item may be to blame.

PS did anybody take a photo of the wiring before it got disconnected?

 

[davecooper]

He says he is happy to live with it as it is and just turn the fan off manually. However, given the chance I would like to get over and investigate further.