After a cut finishes now, a new fan action happens, where the fan seems to run at really high rpms
(maybe in reverse?)for 3 or 4 seconds. What’s that all about? Did I miss a memo?
I need to figure out which fan it is, air assist? Exhaust? Confused.
Definitely air assist, see below.
No reason for either to run backward… By any chance are you lifting the lid before the fan sequence finishes? Doing so definitely allows the fan to speed up. My constant-on exhaust booster speeds up as well whenever I open the lid.
Hmm possibly. I think I open it, then there’s a pause, then the fan kicks on. I should try to repeat it.
Repeatability is good. Standard behavior (afaik) is fan at idle, ramp-up at beginning of job, full tilt during job, then ramp-down to idle after the job is complete (post-photo has been taken and UI indicates it’s ok to open the lid). I’ve never had the fan come on in response to opening the lid.
I heard that earlier and was thinking that it was the Glowforge getting a little hot and it was pushing the coolant through for a few seconds after the cut. I’ll have to look again in a little bit when I make a cut. Glad it’s not the coolant, since I have the air on 73 
(hottest day of the year so far, up to 96.3 right now, heat index of 102)
Think its actually the purge air (the little fan on the back of the head) rather than the bigger air assist fan set further off to the rear.
Hmm I wasn’t aware there were 2. Learn something new every day. @jbmanning5 are you guessing by my video or did you get the same behavior? I wonder if this is an update? Nothing in the UI yet.
I just ran a quick little score job. Seems that it happens with the lid closed or open. I may, or may not have, opened the lid and stuck my hand under there.
At least I left a shroud of mystery as to whether I really did or did not stick my hand in there 
Since the purge isn’t using clean air, I wonder if that last little bit of runtime helps circulate cleaner air through (than you get in the cut / engrave process, at least) and perhaps lessen the need to clean both the lens and mirror in the head. I feel like I’ve had to clean both fairly frequently.
Hmm good theory. Also possibly explains why it waits until the head is homed (and away from the cuts in theory) first.
Would you boys just get your heads down in there so you can see what’s going on? You can tell me all about it so I don’t have to.
Thank you, much appreciated! 
I’ve got a couple. They are an absolute necessity for diagnosing issues with these things, so you should consider going ahead and springing for one anyway. Eventually you are going to need it.
Do you get referral fees from Amazon, @Jules and/or @evansd2? Now, in addition to buying more and more materials, it seems that each time I browse the Community, I end up having to buy new tools at Amazon…
New firmware just came out - v1.4.0-21.
Probably explains the difference.