Does the cooling fan come on when a pre heat from the control panel is done? It shouldn't.
The cooling fan should not come on during preheat and in general is not used until the second layer (PLA).
I ran mine for a bit without the insulation and it had a very hard time maintaining temps.



Quote Originally Posted by Roger36330 View Post
Using microswiss all metal hot end, no insulation around hot end, cooling fan comes on during preheat to keep the warm end below melting point, and heats just fine from the control panel. Btw, using USB cable. So, this is looking like a Simplify3d issue, would you agree?