Extruder temp malfunction

I’ve had no issues with my setup for the last 4 months. Today, while figuring out some janky issues with some Matterhacker PLA, I ran into a weird problem…

The temp for this PLA is 230c (That threw me off, as PLA is usually 205-220.). So after messing around for some time, finally got it (mostly) dialed. Set the print in motion, and about 30 minutes into the print, the temp of the head dropped, almost instantly, to 213c. I couldn’t get it to rise. It bounced between 213-218c for about another 30 min. Then, it restabilized to 230c. It’s been holding for the last hour.

The only difference is that during the drop, it was printing a flat area about 4" radius. it seemed to stabilize when it started printing the walls (think; planter container).

This is the first time the temp ever wavered. Is this a sign of impending failure of the thermister or heat unit?

It can be, in this case you might have been getting too much cooling fan redirected back at your printer head.

First, I sent Lulzbot support an email on a Sunday morning…and they responded within an hour!! That’s nuts! And great customer support.

Second, yeah, after trial and error , looks like I need to turn my cooling down from 100% to 80%. I haven’t printed much PLA so I hadn’t noticed the impact. Well see how this test goes.