I have a 1996 k1500 an my air only blows threw the floor vents a defroster an only blows warm air an it has a very slight tick to it but I can change the speed of the air. It's missing a vacuum line goin into the firewall where the radiator hoses go in on the passenger side an I connected it last night but did no different so I don't know what to do has anyone had this problem? I don't want to take it to a shop cause that'd be to expensive an its not that big of a problem but it bothers me I'd like to fix it can someone help?