Expert: Brad Sears - 11/20/2008

Question
QUESTION: In the process of replacing the thermostatic vacuum switch inside the air cleaner, I lost track of which way the two vacuum lines attach to the two ports of the switch.  While the outside diameters of the ports are the same, one port has a reduced (pin-hole) orifice and the other appears normal.  The switch appears to control the hot/cold air damper in the air cleaner snout, and may also tie in elsewhere.  I have visited dealers, Chilton, Mitchell, Haynes, & the library to no avail.  Obviously, I would appreciate your advice for attaching the vacuum lines to the TVS properly.  Since I'm still in the process of checking out the entire emission control system and have questions beyond the scope of this exchange, could you point me in the direction of any public resources for the theory and operation of the entire system of vacuum lines & devices?  Thanks in advance for your help.

ANSWER: Have you looked under the hood for the factory installed emissions decals? They are mandated by federal law. It should have the vacuum hose routing on it. If the decal is not there check the parts department of you local Chevrolet dealer with your vin in hand.
Brad

---------- FOLLOW-UP ----------

QUESTION: thanks, Brad - re the 1986 Chevy C-10 262 V-6 emission controls system, the decal is long gone; and, several dealers have told me it's no longer available(?) - in any event, I appreciate your time, and if you can lend anything to the TVS vacuum line question, I could still use the help.  Thanks

Answer
Motors Auto Repair manuals published some good emissions books in the day. I have had luck finding these books. One good source is www.books4cars.com. Also check a copy of Hemmings Motor News the old car hobbies classified bible. they have ads for a couple of dozen book sellers. Also you might want to check your public library.
Brad