In our new house, the bathroom fan goes on about 3 minutes after the light has been switched on (single switch for both), and goes off about 10 minutes after the light has been switched off. I would like to decrease the latter duration to something 3 minutes, or even remove the timer function so that the fan is only on while the light is on.
However, the fan is behind a casing that has no screws or other bits that can be removed. I tried pulling it lightly, but it wouldn't come out and I don't know if popping the lid out from the edges with a screwdriver won't break the lid or damage the fan behind.
Is it likely that any adjustable timer setting would be behind the case, or is that just a 'constant' built into the fan circuit? Ultimately, I would prefer to deactivate the fan altogether than to have it run for so long, but I'm not sure how the lid (pictured below) is meant to be removed.