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alkaba
(@alkaba)
Eminent Member
Horrendous smell of the AC bed

Hi,

I just wanted to ask, if your printer also smells like burning acrylic. I had my first C1L shipped about 2 months ago. Initially was everything okay, but after around 2 weeks it started to smell horribly  It was also throwing "AC link lost" faults and ruining my expensive prints from nylon. So i returned this printer to Prusa. They've send me a replacement printer (that was nice from them). Everything was okay, but now the same horrendous smell has appeared on this new printer after just 1 week. I have a feeling, that it needs to be a "feature" of all the C1L. I highly suspect the orange insulation under the heated bed. I print only nylon, so the heated bed is all the time around 115 C and chamber 60C.

I am really sad, that i have to go through this. I love the print quality (just awesome), but these things just bother me and i even had thoughts about going the different route... I cannot sit near my printer, it smells really bad and toxic. 

Is there anyone else, who prints from higher temp filaments and having this issue?

Engineering filament freak
1x Prusa Mini (HT modded)
1x Modded MK3.5 "HT" (450C nozzle temp)
1x Core One L
1x Modded Core One + (70C chamber temp, 450C nozzle)
Posted : 01/06/2026 5:20 pm
Diem
 Diem
(@diem)
Illustrious Member

Contact Prusa Support via chat.  A single instance 'fixed' by replacement may get written off as happenstance but a repeating/repeatable issue gives them something to work with.

Cheerio,

Posted : 01/06/2026 6:22 pm
alkaba
(@alkaba)
Eminent Member
Topic starter answered:
RE: Horrendous smell of the AC bed

Yea, i will write them again. But i think i maybe found the culprit. Its 99% the same "death smell" as with Vorons. Seems, that its coming from the adhesive (probably also 3M 468MP) used on the heatbed. That adhesive starts to smell from 115C and above and never dissapears. So i am again stuck with a death smelling printer. This is a problem, Prusa needs to fix. And I am convinced, that all the printers are affected. 🙄 I think more cases will appear with the HT hotend and people starting to print HT materials with the necessity of high bed temps...

Engineering filament freak
1x Prusa Mini (HT modded)
1x Modded MK3.5 "HT" (450C nozzle temp)
1x Core One L
1x Modded Core One + (70C chamber temp, 450C nozzle)
Posted : 01/06/2026 6:30 pm
Ruebarb
(@ruebarb)
Estimable Member
RE: Horrendous smell of the AC bed

My C1L smells really bad, though I only noticed it after I was printing CF-ABS, just a half spool, even weeks later I could still smell it. So I was atributing it to that. Even now, after printing pla and petg for weeks, when I open the door after a day or 2 later, there is a bad smell, though it has improved. I did make an ABS side panel from the filament and added the creatilty heater, alot of variable to say which is causing the stink. I think more it absorbs odors very well, possibly the acrylic panels. Nylon does produce an odor.

Core One L MMU3, MK3S

Posted : 01/06/2026 6:34 pm
hyiger
(@hyiger)
Famed Member
RE: Horrendous smell of the AC bed

ABS out-gasses styrene even after printed. PC and nylon also have this issue with out gassing. 

Posted : 01/06/2026 6:38 pm
alkaba
(@alkaba)
Eminent Member
Topic starter answered:
RE: Horrendous smell of the AC bed

Well, i have two modded Core One's and no smell even when i have my bed @ 120-125C (my typical temperature because of no active chamber heater). I know, how the nylon smells. This is just not it. Its coming from the bed.
Ruebarb: Same story like mine. I think you "activated" the adhesive with higher bed temp (110-115C) and it will now stink like burned acrylic.

Engineering filament freak
1x Prusa Mini (HT modded)
1x Modded MK3.5 "HT" (450C nozzle temp)
1x Core One L
1x Modded Core One + (70C chamber temp, 450C nozzle)
Posted : 01/06/2026 6:41 pm
Ruebarb
(@ruebarb)
Estimable Member
RE: Horrendous smell of the AC bed

The idea that the adhesive at high temp, is the culprit is a very interesting one. I did do a heat-up the printer to try and cook off the ABS smell at one point and it the small got worse, which I was confused about.  This could explain why I can't get it to go away. I had to improve the advanced filtration and run a room air filter to compensate.

Core One L MMU3, MK3S

Posted : 01/06/2026 6:44 pm
alkaba
(@alkaba)
Eminent Member
Topic starter answered:
RE: Horrendous smell of the AC bed

Yep, now its sounds 100% the adhesive. Try to google "Death smell Voron" or "3M 468MP smell" and you will notice the same symptoms and smell description. Once you go around the 115C mark, the smell will likely never dissapear. So even if Prusa would send me 10 new printers, they all would smell the same after a while. 

Engineering filament freak
1x Prusa Mini (HT modded)
1x Modded MK3.5 "HT" (450C nozzle temp)
1x Core One L
1x Modded Core One + (70C chamber temp, 450C nozzle)
Posted : 01/06/2026 6:48 pm
Ruebarb
(@ruebarb)
Estimable Member
RE: Horrendous smell of the AC bed

As I think back, the smell was the worst while the printer was just sitting there reaching temp. I actually changed the G code to run the filtration while heating up, to help with the smell.

Core One L MMU3, MK3S

Posted : 01/06/2026 6:51 pm
alkaba
(@alkaba)
Eminent Member
Topic starter answered:
RE: Horrendous smell of the AC bed

I have found a quick and dirty temporary "solution". Throw a big blanket over the printer, install the advanced filtration addon and swap the filter around (charcoal closer to printer) and run the fan at 40% all the time. But this needs to be adressed and the Prusa development team should know about this issue. Because like i wrote, this WILL be a big problem with the official HT hotend released. Also we should not solve these problems on a 2000 usd printer... 

Engineering filament freak
1x Prusa Mini (HT modded)
1x Modded MK3.5 "HT" (450C nozzle temp)
1x Core One L
1x Modded Core One + (70C chamber temp, 450C nozzle)
Posted : 01/06/2026 7:37 pm
alkaba
(@alkaba)
Eminent Member
Topic starter answered:
RE: Horrendous smell of the AC bed

I have found a quick and dirty temporary "solution". Throw a big blanket over the printer, install the advanced filtration addon and swap the filter around (charcoal closer to printer) and run the fan at 40% all the time. But this needs to be adressed and the Prusa development team should know about this issue. Because like i wrote, this WILL be a big problem with the official HT hotend released. Also we should not solve these problems on a 2000 usd printer... 

Engineering filament freak
1x Prusa Mini (HT modded)
1x Modded MK3.5 "HT" (450C nozzle temp)
1x Core One L
1x Modded Core One + (70C chamber temp, 450C nozzle)
Posted : 01/06/2026 7:37 pm
Diem
 Diem
(@diem)
Illustrious Member

Yea, i will write them again.

Don't email, use Chat.

Cheerio,

Posted : 01/06/2026 10:14 pm
mildly angry possum
(@mildly-angry-possum)
Active Member
RE: Horrendous smell of the AC bed

Encountering same odor, I suspect. Was this resolved?  What was outcome?

Posted : 04/06/2026 10:42 am
Ruebarb
(@ruebarb)
Estimable Member
RE: Horrendous smell of the AC bed

Please use the chat and report the noxious smell to Prusa CS. It will take alot of convincing for them to even recognize it is a problem, nevermind do anything about it.

Core One L MMU3, MK3S

Posted : 04/06/2026 12:05 pm
mildly angry possum
(@mildly-angry-possum)
Active Member
RE: Horrendous smell of the AC bed

I did reach out to them last night via chat, supposed to hear back from support team by email with fix/resolution. I did some test without any filament loaded just heating up printbed.  Def not filament.   Had to limit my time doing test for support since the fumes/odor was giving me a huge headache. 

Posted : 04/06/2026 12:12 pm
Ruebarb
(@ruebarb)
Estimable Member
RE: Horrendous smell of the AC bed

Do you ever see the bed fans running for chamber temp, I've yet to see them run besides running the test.

Core One L MMU3, MK3S

Posted : 04/06/2026 12:50 pm
mildly angry possum
(@mildly-angry-possum)
Active Member
RE: Horrendous smell of the AC bed

To be honest I haven’t checked.  But last several ASA prints, I kept getting messages that chamber temp hadn’t been reached/wait/skip.  Even after 30+ minutes.  With clean build plate, simple small prints were having adhesion problems.  Finally had to use glue to make them stick.  

Posted : 04/06/2026 12:56 pm
Same Old Shane
(@same-old-shane)
Member Admin
RE: Horrendous smell of the AC bed

 

Posted by: @ruebarb

Please use the chat and report the noxious smell to Prusa CS. It will take alot of convincing for them to even recognize it is a problem, nevermind do anything about it.

Or just have a admin who already submited it as he already said he does report cases from the forums directly internally 🙂 

The issue has already been submitted / reported and as previously mentioned it also happens with other printers as well, it is under investigation to see what is the exact cause of it. We already re-ran a test to make sure there wasn't any health risks, and those came back negative. 

It is has been and currently under investigation to determine the issue, when I have more info it will be shared. 

Shane (AKA FromPrusa)

Posted : 04/06/2026 3:18 pm
Ruebarb
(@ruebarb)
Estimable Member
RE: Horrendous smell of the AC bed

It is a good start, please share the health data, I did another test this morning of 60 chamber and 110 bed and smell is very much still present, though it did dimish a bit over time. My wife is ready to throw the printer outside. I may have to choose soon.

Posted by: @same-old-shane

 

Posted by: @ruebarb

Please use the chat and report the noxious smell to Prusa CS. It will take alot of convincing for them to even recognize it is a problem, nevermind do anything about it.

Or just have a admin who already submited it as he already said he does report cases from the forums directly internally 🙂 

The issue has already been submitted / reported and as previously mentioned it also happens with other printers as well, it is under investigation to see what is the exact cause of it. We already re-ran a test to make sure there wasn't any health risks, and those came back negative. 

It is has been and currently under investigation to determine the issue, when I have more info it will be shared. 

 

Core One L MMU3, MK3S

Posted : 04/06/2026 3:29 pm
alkaba
(@alkaba)
Eminent Member
Topic starter answered:
RE: Horrendous smell of the AC bed

 

Posted by: @ruebarb

It is a good start, please share the health data, I did another test this morning of 60 chamber and 110 bed and smell is very much still present, though it did dimish a bit over time. My wife is ready to throw the printer outside. I may have to choose soon.

Posted by: @same-old-shane

 

Posted by: @ruebarb

Please use the chat and report the noxious smell to Prusa CS. It will take alot of convincing for them to even recognize it is a problem, nevermind do anything about it.

Or just have a admin who already submited it as he already said he does report cases from the forums directly internally 🙂 

The issue has already been submitted / reported and as previously mentioned it also happens with other printers as well, it is under investigation to see what is the exact cause of it. We already re-ran a test to make sure there wasn't any health risks, and those came back negative. 

It is has been and currently under investigation to determine the issue, when I have more info it will be shared. 

 

Yea i have the same problem with my woman 🤔 😀 I think the only solution is to change the adhesive on the bed. I am now really convinced its the culprit... I hope they will solve this somehow. I cannot (again) use my printer... 

Engineering filament freak
1x Prusa Mini (HT modded)
1x Modded MK3.5 "HT" (450C nozzle temp)
1x Core One L
1x Modded Core One + (70C chamber temp, 450C nozzle)
Posted : 04/06/2026 5:19 pm
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