When I open or close the garage door, the light does not come on immediately. It comes on after 2 or 3 minutes. Is there any reason for this? I have changed the bulbs from CFL to regular ones also, but no progress, the issue still remains

Could it be the sensor needs some ajustment , I have the same problem with an outside light when I pass my hand across the sensor it comes on due to the heat from my hand. Maybe it just needs a while to warm up or as I said a slight ajustment is needed.

How do I adjust the sensor? I don't even know where it is located. There is no sensor for the motion, so it has got to be in the door opener itself

Could it be that there are two.. one being a receiver and the two are out of alinement, maybe one is at the bottom of the garage door and maybe the other on the floor somewhere opposite... could there be a battery backup which has ran down needing replacement?

Hi,

Older garage door openers rely on a resistor in the lighting circuit of the opener to put the light on and off. They require a certain wattage bulb to work properly. The instruction manual with your opener should say what that wattage has to be. To my knowledge there is no adjustment that can be made to change this setting.

I agree, there is no adjustment. I'd try a larger bulb which will pull more juice causing the resistor to heat up more quickly.