slow printing cooling slowing printing

[jax521]

Printing envelopes and after about 10 the printer starts slowing down and is showing colling on LCD screen.  is the normal?  the matching has space and is clear of anything blocking air flow.

[Valsimot]

Yes, it's to prevent the heating element ( fuser) from overheating. When you print on plain paper, the paper sheet absorbs a lot of heat on itself, but when you print on envelopes that are narrow, a lot of heat stays in the heating element because there is nothing to absorb the heat from the outside edges of the heating element.