Printing a cylinder - the north side prints fine, the south side is all messed up

[texan_in_exile]

I'm printing off the Apollo Mission from thingiverse (http://www.thingiverse.com/thing:15098) at 200% scale and I've got it almost all done.  Working on the last part, the bottom (nozzle end) of the service module.  All the other parts printed fine including the service module top which I did last night.  Both top and bottom of the service module are essentially cylinders, identical except for their ends.  So this morning I go in to print the bottom, and instead of a nice cylinder I get the weirdness in the attached photo.  The north side of the printer (front of the MendelMax 2.0) prints a nice looking cylinder, just like the one I printed last night, but the south side is a horrible tangly mess. 

What could be going on here?  The printer was undisturbed and powered off from last night's successful print until this morning's disaster.

Thanks,
-Mark

P.S. I'm using Repetier-Host and Slic3r. Here's the settings from Slic3r:

; generated by Slic3r 0.9.9 on 2013-05-13 at 13:49:56

; layer_height = 0.4
; perimeters = 3
; top_solid_layers = 3
; bottom_solid_layers = 3
; fill_density = 0.03
; perimeter_speed = 35
; infill_speed = 65
; travel_speed = 140
; nozzle_diameter = 0.4
; filament_diameter = 3
; extrusion_multiplier = 1
; perimeters extrusion width = 0.42mm
; infill extrusion width = 0.42mm
; solid infill extrusion width = 0.42mm
; top infill extrusion width = 0.42mm
; first layer extrusion width = 0.80mm

[texan_in_exile]

Should add, 3mm PLA, 190C 1st layer then 185C extruder temp, bed temp 85/80C.  I've tried it with continuous fan and no fan (40mm fan mounted up on the extruder carriage).

[Misha]

Is your fan blowing from the south or north on your carriage?

On Monday, May 13, 2013 5:23:18 PM UTC-5, texan_in_exile wrote:

[texan_in_exile]

Fan is on the north side, blowing from north to south.  From front of the machine to the back.  It's a fan mounted to the extruder.

[JohnD]

Stick a fan on the south side of the part.  I'm a firm believer in the BigArseFan theory for PLA.

On Tuesday, May 14, 2013 5:03:20 AM UTC+1, texan_in_exile wrote:

Fan is on the north side, blowing from north to south.  From front of the machine to the back.  It's a fan mounted to the extruder.

On Monday, May 13, 2013 10:01:23 PM UTC-5, Misha wrote:

Is your fan blowing from the south or north on your carri

[Greg. L]

Yeah, that looks like a textbook case of your PLA being too hot as each new layer is put down, caused by a void in the air path. More fans is a great start, followed by making sure that they're not pointed /directly/ at each other - you don't want a dead spot in the air where the pressures fight it out. Offset them all from the center line ever so slightly.

[Russell Shipe]

Turn your bed down or off. It helps pla cool. IMO only use as much heat on the bed as you need for first layer to stick. (For pla)

[Russell Shipe]

Oh and bigarse fans lots of them