PETG problems after partial MK3 -> MK3S + MMU2S upgrade
I have a pre-built MK3 (Dec) and my MMU finally showed up a few weeks ago.
Prior to starting the upgrade I ran out my first PET-G (Amazon) parts and it worked fine using the Prusament settings.
I rebuilt and reinstalled my extruder with the MK3S parts, but have not yet installed the MMU itself (wanted to get things dialed back in prior to throwing in that particular hand grenade...). I upgraded the printer to the latest 3.7.0 MK3S firmware. I've also been running with the filament sensor off.
After getting my bed leveling dialed in I ran off a bunch of "life Z" tests and XYZ cubes trying to dial in my axis (Y is still off due to bearing play ☹️) in PLA with no issues.
Then I tried to print some PET-G parts and things did not go well. The first few 0.2mm layers (5 I think) of the parts appeared to be fine, but the small support areas (2% of the print maybe) were a mess. Most of the interface layer on the bed stuck, but the structure layers didn't. In some cases it stuck to the interface enough to rip it up, but it looked like most just gunked up on the nozzle. I checked on it after the 2nd layer had started and noticed that the fan hadn't kicked on like I'm used to with PLA (and I don't recall what it did on the pre-rebuild) so I manually turned the fan on to 100%. When I came back I found the mess and stopped the print.
Today I ran another PLA print with no issues, but when I ran another PET-G print (no supports this time) it messed up again. I wasn't as proactive about it and checked on it after about half an hour. 10 of the 12 parts were doing fine, but 1.5 were missing and there was a blob being drug around. I also noticed that the part fan was again not running (4 layers in) and the extruder temp was up at 260 and climbing.
Any ideas why I can't seem to print PET-G now and why the part cooling fan isn't turning on?