Brand-new air conditioner (window unit) blows air but doesn't cool it - is there a reason?

My landlady's husband just installed a new window-unit type AC in my apartment. We ran it for about 20 minutes while he was there, and it never started to actually cool the air down. He and the handyman then told me that often new air conditioners that are shipped/stored on one side need time for the coolant/freon/whatever to settle back into the coils (or whatever). I just ran home a little bit ago - about 3 hours after it was installed - and it still wasn't cooling air. Were the guys right - do I just need to wait a bit longer - or can we officially say this sucker is malfunctioning?