Miller Syncrowave 351 Owner's Manual page 28

Trouble
Tungsten electrode oxidizing and not
remaining bright after conclusion of
weld.
Fan not operating. NOTE: fan only
runs when cooling is necessary.
OM-354 Page 24
Shield weld zone from drafts.
Increase postflow time.
Check and tighten all gas fittings.
Properly prepare tungsten.
Check for water in torch, and repair torch if necessary.
Check and remove anything blocking fan movement.
Have Factory Authorized Service Agent check fan motor.
Remedy