1994 Volvo 940 Station wagon -- picked it up from service yesterday -- had engine gasket, spark plugs, replaced -- oil changed. Didn't notcie that air conditioning wasn't workign compltely properly - it's cooling and pushing air out top and bottom but not main vents. Asked ? online and found were told that vaccum hose was disconnected or leaking from engine manifold to firewall--- actually appears hose is missing completely -- we have connector on engine manifold but can't find place on firewall that it would be connected -- assume we can get part from a auto parts store...we're trying to leave on a trip...we need to know where place on firewall to look for connecting point...

Optional Information:
1994 Volvo 940

Already Tried:
tried connecting a plastic tube from engine manifold vaccum point to a place on firewall but couldn't tell any difference in AC