Hi im new to these forums and i have a 1992 silverado and my heater core under my dash the cover is broken and i fixed it with some electrical tape and idk if any fluids are in there but i dont see any leaks anywhere but am i losing any blowing air or anything by doing that? because my very left vent isnt blowing as much air as the other ones please help me

 

Putting tape on the cover is not the cause of losing air flow. Does the left vent have a shut off control under the vent if not then it could be that either the air duct is mismatched somewhere under the dash or blocked. You'll probably have to dismantel the duct work.