ℹ
info HP
Status Printing... Cool down mode
Printer is in cool down mode during printing — temperature regulation in progress.
? What Causes This
Internal temperature has risen and printer is cooling before resuming printing.
ⓘ What This Means
No action required. Wait for the printer to cool and resume printing automatically.
Source: page 8 of the official manual
From the manual
This error code appears in:
HP Color Laserjet Pro M255 M256 Printer