Your answer about the fan stopping and starting is not clear. Does the fan run constantly even when the unit is at the correct temperature, or does the fan turn off when the correct temperature is reached?
When the incubator is working, the fan will rotate to dissipate heat and cool down. If the temperature is reached, the machine will stop working and the fan will stop running.
Are any of the electronics on the top of the incubator where the handle is? I would be looking to cut a hole into the top to shine a lamp through and wanted to make sure this would not disrupt the functioning of the product.
