# Specific 3D Printers, Scanners, & Hardware > MakerBot Forum >  Replicator 2 Fan Direction?

## Chemvaldes

I was reading in another thread where somebody posted that the fan should be installed with the sticker facing inward. I assume that means against the heat sink. My fan is facing outward (readable under the cage) and the fan sucks air from the heat sink (I believe).
Regardless of the side the sticker is on how does the machine come from the factory? Does the fan pull hot air from the heat sink or does it blow air against it?
I am talking about the fan that is faces the front of the machine and not the side blower.
I just found a picture of my machine when it was three months old and I can't see the sticker but i have no idea if I would have taken it apart by then.
20140809_01.jpg

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## Mjolinor

It should blow air into the head from the front of the machine.

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## Chemvaldes

Thanks Mjolinor for the quick reply. I have mine installed backwards and while it has worked I will flip it around. I've had the machine for over a year and must have been running it with it sucking from the heat sink for 9 months or so or since the first time I took it apart.

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## thinkdifferent

Yes, it happened to me  :Frown:  

Thank you this post.

I give another reference:

http://support.freedspace.com.au/kno...er-head-replic

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## Mjolinor

I run mine backwards sometimes because I printed a dodad that blows the air down onto the print from the other side of the fan. I don't need it for ABS but put it on for PLA sometimes.

It doesn't seem to make much difference to the job it is supposed to do.

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## Chemvaldes

I have about 30 hours of printing with the fan in the correct position now and i have not noticed much of a difference if any in the print quality. I only print in PLA and I print in a cold room with low humidity.

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## Chemvaldes

Thanks for the link Thinkdifferent.

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## thinkdifferent

The problem is not quality: In long printing times, Temperature of the extruder increase and feeding PLA material can be melting. So Nozzle can clog. I've same problems in 6 hours prints. IMG_4810.JPG

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## MBSupport

Hey guys make sure the silver sticker on the fan faces the heat sink blades. 

Here's a picture showing the correct assembly extruder order:

Extruder Assembly Order and Orientation.jpg

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## MBSupport

> The problem is not quality: In long printing times, Temperature of the extruder increase and feeding PLA material can be melting. So Nozzle can clog. I've same problems in 6 hours prints. IMG_4810.JPG


It sounds like your extruder is overheating. Please make sure that the fan is installed properly, your prints are running at 230°C and you have ceramic insulation tape securely fastened to the heater block.

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