We wanted to test the post process properties of PVA but did not want to print anything. We unloaded the ABS that was in the printer and then started loading some PVA. After the PVA was loaded we let it keep going through the loading process until it pushed all the PVA out and we had our test sample. We then stopped the loading process and started the loading process again to put the ABS back so we could continue with normal printing procedures. Now, the ABS will not load into the right side and started making a clicking/ticking noise. Our printer is a Flashforge Dreamer. What is wrong with my printer and how can I fix it?
Run some cleaning filament through the extruder at the printing temperature of your PVA or ABS filament, whichever is greater, until the old stuff has been completely displaced. Then load the new filament until the cleaning filament has been completely displaced.
This should be done every time you are switching materials, unless you don't mind disassembling the extruder and/or hotend and clean it out manually.