Just as ManinBlack said...Short Circuit hoods do not work. Thet are a poor design and you don't see them installed very often anymore. Is the hood that you are talking about a "face discharge" hood? In otherwords, is it blowing the make up ait out away from the hood? If it is, you can change it to a down discharge by buying a new make up air plenum and installing the duct to the new plenum. About 80-90% of the down discharge make up air is captured by the exhaust canopy if it is installed and working properly.
Make up air is not air conditioning....unless it is conditioned. Also, that grill is radiating heat. Radiant heat will not be captured by any hood. Captive Air make air-conditioned make up air units.
go to www.captiveair.com