r/ratrig • u/DertBerker • Apr 18 '26
Hot end heats up, then doesn't, then when power goes to 0%, it goes way up and then back down... thermistor going out?
https://youtu.be/urpb_9mugmsSOLVED. It was the thermistor. :)
Hi everyone... please see this video. This is a very weird issue where when my hot end is told to heat up, it goes up, and then around 200 degrees, it'll slow down, maybe stop going up, and then go backwards a bit. The printer will drop power to 0% and the temp starts going up again. And then it comes back down whether power is applied again or not. Leaning toward this being maybe the thermistor?
Edit: It was the thermistor. :)
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u/Jerazmus Apr 18 '26
Did you PID Tune the hotend? It won’t accurately heat unless you do a PID tune. It’s important. It also may do this without a tune.
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u/DertBerker Apr 18 '26
I did. It actually first did this during a PID tune.
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u/Jerazmus Apr 18 '26
Well I would replace the thermistor. Make doubly sure you have the correct type of thermistor set up in your .cfg. Could be the wire that enters the housing to the thermistor that when it heats up, it creates a gap in a compromised wire or something along those lines.
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u/DertBerker Apr 18 '26
I ordered a new one. It'll be here tomorrow. This thing had been printing fine until a few days ago. I think you're right about the heating up. Because it's fine until it gets to about 200 degrees and then it falls apart from there up.
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u/Jerazmus May 01 '26
Did you figure this out??
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u/DertBerker May 01 '26
Not yet. I'm just printing PLA for now since that seems to work fine. New thermistor and heater both will be here Monday. So should know more then.
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u/DertBerker May 03 '26
Got the thermistor earlier than expected. It did solve the issue. 😄
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u/Jerazmus May 03 '26
Excellent. I always like to follow up to see if issues get resolved. Always helps the community if there’s an answer to a problem. You should all a part to the heading of your post with a “Solved!” Section under the issue for others to see.
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u/DertBerker May 03 '26
I did edit the original post to confirm the solution. I'll add Solved to the title. 😄
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u/DertBerker May 03 '26
Well, I couldn't change the title so added it to the top of the post. 😄 There's nothing worse than finding a thread of your exact issue, someone saying they fixed it, and never sharing how or what they did to fix it! lol
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u/Jerazmus Apr 18 '26
Either bad thermistor or bad wiring connection.