Vacuum canister..

[nxtlevl]

On my '87 GMC, the round vacuum canister has one vacuum line running out the top that runs over into a "T".....What exactly do these lines run to? Does one operate the blend doors for the heater control and/or????? Was noticing the line coming out of the canister was looking brittle, and was needing replaced...Not that it matters too much right now, because I only have heat (or something close to it..lol) coming out both the defrost vent/floor vent.....I guess I just need to run down and grab some light bulbs for my shop light so I can actually trace them down.......We are having crappy weather right now tho, and I was just being lazy.....I'm thinking next summer tho, I'm going to have to completely go thru the vents/blend doors/actuators, and replace alot of things....I can move the control lever thru all functions, but it still only comes out the defrost/floor vent.............

 

[Manbearpig]

Kinda curious too

My ac controls dont have any vacuum to them

 

[HotRodPC]

Are you talking about the Vac Canister Evap for emmisions off the gas tank aka Canister Purge, or are you talking about a round ball with a vac line? The round ball is known as a vacumm amplifier to the best of my knowledge. And I do beleive it is for things such as moving your vac operated gates in your duct work of the heater, AC and defrost system. Some vehicles you will also see that for the windshield washer operation or crusie control, and can aslo be used for other emmisions like EGR control or exhause heat riser valve that blocks the exhaust off a bit to keep the heat up near the head a little longer. So those vacuum amplifiers can be used for many differant things on different makes and models of vehicles if that is what you are reffering to.

 

[nxtlevl]

Are you talking about the Vac Canister Evap for emmisions off the gas tank aka Canister Purge, or are you talking about a round ball with a vac line? The round ball is known as a vacumm amplifier to the best of my knowledge. And I do beleive it is for things such as moving your vac operated gates in your duct work of the heater, AC and defrost system. Some vehicles you will also see that for the windshield washer operation or crusie control, and can aslo be used for other emmisions like EGR control or exhause heat riser valve that blocks the exhaust off a bit to keep the heat up near the head a little longer. So those vacuum amplifiers can be used for many differant things on different makes and models of vehicles if that is what you are reffering to.

Yep..the round ball with a vac line. I was just curious, because this was the only Vac Canister under the hood, and wasn't too sure what its purpose was....The emissions canister is AWOL, probably from the original builder of the truck...Thanks for you help!-----------------------

 

[HotRodPC]

Yep, that is just a vacuum amplifier is what it is. The Evap Canister usually sits behind the headlights on the dirver side under the hood on SquareBodies. Many times, or older Fords, they'd what looked like a black painted juice tin can for vacuum aplifiers. And that was facotry OEM.