Mike's PCjr Page

The PCjr. fan is intended to keep the disk in the drive cool when it is in a confined space. The fan can be turned off by unplugging the connector from the board. When done, the system runs completely silently (absent electrical noise, floppy disk drive access and sound circuits). It is the only PC compatible desktop system from the 1980s that I know of that can be to run silently easily (the Tandy 1000RL and RLX hail from 1990).

Has anyone actually melted or physically damaged a disk in the drive after heavy usage?

I doubt that anything will melt. But IBM included the fan for a reason, probably because the heat causes premature aging of the components in the drive and the media. Later revisions of the machine included a fan shroud to improve the airflow through the drive indicating that this was a real concern.

It is not designed to run fan-less unless there is no floppy drive and controller. The fan is attached to the reason tray for a reason.

It should be reasonably easy to replace the fan with a much much quieter one that meets the CFM requirements of the original. It's certainly one of the louder case fans I've seen.

If you are not using the floppy drive regularly, is the heat from the rest of the system likely to cause damage? jrIDE can handle most of what is needed.