Brown Hard Liquid at back of machine and now exhaust fan isn't running right

Help! I turned on my Glowforge this morning and the light was blinking orange. I searched the forums and it suggested to make sure that it was clean. I went to unhook the exhaust hose to clean the fan and I found a brown hardened puddle at the back of the machine. It was also inside the exhaust that is vented outside. I cleaned it really well and was finally able to get the light to go off. So I decided to try a test project to see if it would work. It engraved, but the exhaust fan will now not blow hard enough for the fumes and smoke to go out of the machine in the back…ugh…I have several customer projects due at the end of this week and the coming weeks. I don’t know what to do. The exhaust fan and the whole left side is extremely dirty but you can’t get to any of it to clean it. I have been chatting with support and they had to refer me to a sneior associate because they couldn’t help any further. Anyone else had this issue? Anyone know how to get to the exhaust fan to the left to clean it other than from behind?

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Paging @Jules - she wrote up a pretty detailed process to clean the fan.

Yeah, I’m here, but I’m not going to give instructions on how to clean anything until support determines what the brown liquid is. ( And I wouldn’t try to use the machine until they get back to you.)

Did you check the inside of the hose itself to see if there is a similar liquid caked on anywhere inside it? Perhaps with a hole or split in the hose? Is it possible that rain came into the hose from the external port and you have a leak in a low spot? Could that be condensation inside the hose from a large temperature differential between the inside and outside temps?


This looks exactly like the stuff I get in my smoker. It’s likely cresote that’s generated from the pyrolysis of wood products aka burning of wood…

Like @Jules mentioned it could be from condensation buildup on the hose and leaking back into the machine (and condensation on the fan as well).
Cresote is water soluble so you should be able to take a damp cloth and clean it up slowly.
I don’t know what support will say about cleaning the inside… I’d be concerned that the fan has gotten some of it in areas you cannot clean.

Preventative measures:

  1. Now if this is indeed a condensation related issue I would suggest that you actively block the outside elements from coming in by ensuring that the hose is disconnected from the outside when not in use or that there is always positive airflow out.
  2. The hose should be positioned such that the lowest part of the hose sits below the bottom of the GF. Kind of like the trap under the sink, it just needs to be a slight dip (1-2 inches should be ample). This way if there is condensation, it will accumulate in the U rather than pooling back to the machine itself, once you start running again the positive air movement out should help dissipate any accumulated moisture. Again this won’t solve any issues with condensation occurring inside the machine itself.

Sorry to hear that you’ve hit a snag. I see you’ve already received some good advice so far from @Jules and @PatrickN. Pnotton’s advice on making sure to disconnect your exhaust hose when not in use matches our recommendation. Cleaning your fan as a next step is a good idea. Regarding your question on how to do that, you can clean your fan using the following steps:

First, you’ll need to obtain a can of 3M Novec Electronic Degreaser, which you can purchase from Amazon or Digikey.

That page will walk you through the cleaning process. Brief summary:

  1. Turn off and unplug your unit and move it outside. Make sure it’s in a location where it has power and Wi-Fi

  2. Using the fan maintenance page, you’ll be able to turn the fan on

  3. Following all manufacturer’s safety instructions from 3M, spray the degreaser into the fan while it’s running for approximately 5 - 10 seconds, or until the fan is clean.

  4. When you’re done cleaning, turn off your unit to stop the fan, and return it to its usual home. You should now see considerably better performance from your exhaust fan!

Please let us know how it goes and if you have any questions!

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Hi @gcifers, it’s been a little while since I’ve heard back from you. I hope that’s because everything worked out! Were you able to complete the steps my colleague ivan1 had sent you? If not, just let me know and we’ll get it solved.

It’s been a little while since I’ve seen any replies on this thread so I’m going to close it. If you still need help with this please either start a new thread or email