i have part number 16250595 on the unit on a sticker with prod date or 1 oct 99. does the entire unit have to be replaced or just that mode selector?
also has [art number 16233939-a molded in the plastic...which one do I use

 

Everything in the image above, it's all one piece. GM part #15098966


http://www.gmpartsgiant.com/Page_Pro...&mCode=TT10506

 

mine has the rear defrost button too, does that change the part number?

 

In the lookup it didn't mention with or without rear defrost. Probably be best to check with a local GM dealer. You'll pay through the nose there, so maybe they will just give you the correct part number. Or you can try a boneyard, you know how to test it now

 

found one on amazon brand new, i cant even begin to thank you captain! always clutch with helping us out on here! will let you know how it goes when it comes in!!

 

2000 rear defrost must have been standard equipment.

 

new unit came in, im not sure if its my connection which to me looks snug, or the new unit. but i did the vacuum test where the black line enters the new unit, was not holding pressure when put on bi level (floor and vents). the vents are switching but when on ac, max ac and bi level its still coming out of the defroster, not as much as before, but still coming out. when on defrost its defrost only and it also works when floor/ defrost.

not sure if the new unit is bad, or something else. let me know what you think captain

 

also just did the test from the small plastic line under the hood with everything from the hvac control connected, it leaked 7 after 10 minutes

 

Just for grins, put the mode switch on windshield and floor, (just before defrost position). Apply vacuum to the black port on the mode switch. See if that one holds.

 

just gave it a try on the new one, did not hold vacuum either