Very recently I ran a couple of prints with Polymaker’s PC-Max with a max temp setting of 270deg. A day later, the printer failed as the heating had failed. So I manually set the temp to 250deg and I got the error when the temp had reached around 210. I did this a couple of times and kept getting the same error. (Btw, I have a Lulzbot Mini v1.04, basically the latest release without LCD prior to the Mini 2).
I then decided to set the temp to 210, which it reached without error albeit it did seem a little slower than usual. Then I upped the temp to 220 which it reached, then to 230 and I got the heating failed error again. I repeated this process using both Octoprint and Cura. I repeated the process after updating the firmware via Cura as well. In all instances, I get the same error.
I have been in touch with support and the replies are really really slow. At max it is 1 email per day. I am sure they must be really busy but I need to get the printer working again. They had asked me to check the resistance of the heater cartridge and thermistor. Both were fine. I was then told it is the environment that is preventing the hot end from heating up i.e. really cold or I have a fan/vent at or near my printer. Neither is true as the printer is on my desk in an office type environment at room temperature. No fan and not near any sort of ventilation. Sometimes it gets a little warmer but it is never cold. The printer has previously printed Nylon in my workshop and where the ambient temp has been as low as 5deg.
The temperature increase is not sporadic but rather a smooth curve with no sudden drops. It just seems that it is taking a little bit longer to heat up and that is triggering a heating failed error.
Is there anything I can check to diagnose what the problem is? Another thing I noticed is that the fan inside of the electronics enclosure does not come on anymore. Maybe it’s a mute point but usually it used to fire up either immediately or very soon after the printer got going.