Vacuum issue

THE SALMON

MEMBER
1999 GMC YUKON
5.7L
V8
4WD
AUTOMATIC
207,000 MILES

Just overhauled the engine but did not mark, or the tape fell off, 1 vacuum line and 1 vacuum port.
My PCV valve connects to the usual connector on the intake, but that connector has another tube that looks like a vacuum hose connects to it. What connects to that port? I also have a plastic formed tube with an rubber connector on the end. It's a little over a foot long and seems to snake around or through the engine. I kept it on the passenger side of the engine bay while doing the rebuild.
Thanks in advance.
Carl

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3 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

Good evening,

I attached a vacuum diagram for you to view. See if it helps you find the routing for your hoses.

Roy

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Thursday, December 12th, 2019 AT 3:00 PM

JIS001

MECHANIC
3,411 POSTS

If my memory is correct, that extra port is for the plastic vacuum line for your HVAC control for the blend doors. So if you were to start your vehicle and turn the A/C on then all the air would blow to the defrost.

When I worked at an independent shop I would remove the plastic vacuum and just run a rubber vacuum hose from there to the HVAC. Let us know if that is the case. And to be honest, the other end without the rubber looks broken. You will need to attach a rubber hose from that end to the HVAC if there is still enough hose at the end to attach.

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