How to seal gaps in between bricks of fireplace vents.?

I have a fireplace that uses blowers and vents. The vents on the bottom are supposed to suck in cold air from the room. They usually only blow out cold air while the top vents do blow out warm air. I have sealed the bottom vents with mortar to prevent the cold air from being blown out. I still have the blower motors in behind the mortar now since the only way to remove them would have been to remove bricks. Is it ok to just leave them in there?