When I pull a vacuum I get good AC flow out of the front vents, otherwise the AC is air is low, in which case it appears to be coming out the front window vent.
What do I need to do/replace to have the air consistently come out the front vents?
Thanks

 

Find and fix your vacuum leak. Start with the line coming out of the firewall in the engine compartment and work your way out.

 

This should help you find the leak.

 

Thanks to all!
Found it, lost connection to reserve tank.
Fixed just in time for heat!

 

Thanks for the update.