I was using my paslode IM250A nailer todat when the fan stopped functioning properly. Fan still worksbut spins very slowlyand gun will not shoot nails.

Try this link for an exploded drawing.
https://www.toolpartsdirect.com/paslode-im250a-impulse-angled-finish-nailer.html

Isn't it suppose to? Inatall the bat and wait 2 to 4 min and see if it shuts off.

Can denotes the motor has gone

are the fan blades bent causing a vibration. you can run the fan with the cylinder off to try and isolate the noise. Let me know

You have a stuck head switch - it is part of a circuit assembly (#89), it may be the actuator (#66) causing it.
https://www.toolpartsdirect.com/paslode-90060-cordless-16-gauge-angled-finish-nailer.html

strip it down again and put the battery in and whilst holding the nipple down pull the trigger (just mind your fingers as the fan will start) and as you squeeze the trigger see if sparks each time

Any time these guns become intermittent or stop firing but the fan still runs, the first the to check is the expiration date on the gas cartridges. The do expire and this will make the gun work inconsistently or not at all.

try a new battery m8 when they have been used fir a while they wear out at the catch and when u fire the nail gun the battery works its way out enuf to stop it making a good contact. Hope this helps.

ther is a depth adgustment on the front of the gun,try lowering the adjustment tip a little at a time.see if that works.