I had few printing troubles for first layer yesterday (will certainly ask there as soon as I can take photos) but one of the things I've noticed is that the model cooling fan (the fan that is supposed to blow air on the printed model, not the fan that regulates the noozle temperature) is turned off for printing the first layer.
It's a Dagoma DiscoEasy200, printing PLA on a non-heating bed (blue tape).
Wandering down stackexchange, I also read
turn off the part fan for the first layer from https://3dprinting.stackexchange.com/a/5494/10836
So my question is:
what's the reason behind turning off the part/model-fan for the first layer?
Filament expands as it gets hot. Cooling the filament will make it shrink, so cooling the filament deposited on the bed can lead to adhesion problems and warping of your products. This is exactly the reason why you use a heated bed (the delta temperature is smaller). So keep the cooling off for the first layers and you'll be fine.