No need to be rude.

Educate yourself.

Glad you found the issue with the fan.

For the fan issue in the file itself as I stated and posted a screen shot for you, Simply 3D allows you to control the fan speed layer by layer of you want.
I setup OctoPrint on an RPi (hence the name OctoPi) and send my files to be printed directly to the printer through that instead of the SD card route.
It does not like the x3g files and instead uses the gcode files. S3D has the ability to save both the x3g and the gcode file at the same time.
Fan on/off and speed settings work on the gcode file. The x3g its either on or off. I've not looked into seeing if you can pack the speed control in the x3g file.

Glad your up and running again. Enjoy.

Quote Originally Posted by JensC View Post
Reality Check (back to the thread topic)

1. Answer to my first original question:

The aux cooling fan plug near the extruders was defective. At rest it worked but when jerked around by the head in certain directions the fan power was intermittent. Fixed.

2. Answer to my second original question:

The code to turn on the aux cooling fan is M106. The code to turn it off is M106 S0.