I found a few similar issues listed in the Problems and Support area, but they have all been closed. I went through all of the same steps and have not been able to resolve the issue. I have cleaned both fans, checked the contacts for the head, and the issue persists. Were you able to resolve any of these issues after receiving a unit back?
Thanks,
Common problem noted recently is that strong magnets on the bed can pause the air assist fan if it travels over them during the print, triggering the warning. Are you using magnets to hold down the material?
I am. Support just asked me to try printing without them, and that worked. I am a little concerned now… using magnets to hold down my material has become an important part of my work flow. Trying to figure something else out is probably going to be complicated. I’m definitely open to recommendations.
As an aside, how are you able able to respond in this forum so quickly??? I have been watching the forum for years now and your ability to respond to so many topics astounds me! 
Chuckle! I have some of the categories set to Watching status. It causes a little pop-up in the lower right corner of my screen, and I speed read. 
You might want to give the Honeycomb Pins a try to hold your material down. I use them instead of magnets, and they work great, even on warped materials. (All of my stuff gets warped here from the humidity.)
What kind of material? How big?
The important thing is having the magnets placed so the fan doesn’t go over them. I’m still able to use them, but I only use magnets on the far left and far right of material. You could also use them on the front of the material with no problem.
I do have some of those… but for most of my prints they wouldn’t work. Most of what I cut out are parts for small foam RC airplanes. What this means is that what I need to be held down fills the entire printable area (20 inch x 30 inch sheets of foam board).
If you put spray mount on a board and stick your foam to it you can hold down light material without magnets. It can take a few tries to get the right amount of spray mount so it stays down but easily comes up after cutting. But once you figure it out it is easy to repeat. You can also purchase mats that do the same thing but they are expensive.
I have never been a fan of the magnets for holding things down, there is way too much electronics in there that could easily be thrown off by a magnet.
Foam is very easy to poke a hole through. (I know that grinds some people’s teeth, but it’s very effective.) You could also stick it on a sticky mat to hold it down.
Or keep using the magnets, but block them with some film or aluminum tape. Might be enough to keep from capturing the fan.
Ok, I’ll start figuring things out from scratch again. Glad it’s going again, though. Looks like my next print will be some more of those pins. I’ll try to find a way to put some in the middle of the prints. Thanks!
So the material isn’t warped… just put a magnet on the far left edge, far right edge and in the front. The left edge is a no-go zone already. The front won’t have the fan go over it because it’s impossible.
How many magnets are you using? I hold large sheets of chipboard down with just 2.
One thing…when you’re using the pins on material that’s thicker than 1/8", (which the foam might be, I don’t know how thick of a foam you’re using)…it helps to have properly sized pins.
I modified the shaft on a set of pins for use with 1/4" material pinning, and they hold better. If you’re cutting thicker foam, they might work better to hold it down without crimping it.
Honeycomb Pins Long jmz mod.zip (43.8 KB)
This is awesome! Thanks Jules!
I have always used two: one to create the necessary holding power, the second to prevent the foam from twisting upwards on the opposite sides. There are times when a single magnet works, but usually I have needed two. Going to give Jules’ modified pins a try now.
I just printed off a batch of those pins and then ran a job with the foam using them… and they worked awesome! Thanks again!
Excellent! 
(Probably should have posted them earlier but it just never occurred to me.) 
This just happened to me… Ruined a print. Would be great if there was a better way to pause the print to remove the magnet without having to start over.
Trying the hold down pins shortly, thanks for the link!
Thanks for the answer @Jules. I’m going to close this thread - if the problem reoccurs, go ahead and post a new topic.
We try to keep to one topic per post in the Problems and Support section. If you have an Air Assist Alert while not using magnets can you create a new post with that question?