I apologize for the delay in the reply to this message. I can't say I rightly know the answer to your question! I hope you've found the answer to your question by now and that things have been fixed!
Springthing. You reccomended by another member. I have a 1998 surburban 5.7 engine frt and rear air. Where does the vacumn hose from the heater control valve connect to. I have air box off and donot see any vacumn ports. Thanks