From what I remember, I was told that the air pressure switch (APS)should be closed when boiler is running correctly but will be open if the LED on the control unit flashes and hence has an APS fault. (I think I should check this when the boiler is off to ensure I've got this the correct way round!).
So I would check the electrical connection of the APS is open circuit to confirm a fault but I guess I'd have to do this very soon after the fan starts up as the fan needs to be running for the test to be valid.
So I would check the electrical connection of the APS is open circuit to confirm a fault but I guess I'd have to do this very soon after the fan starts up as the fan needs to be running for the test to be valid.
