Where's the 2 plastic vacuum lines under heater box go?

[HAFROD]

Guys, I cannot remember where the two plastic vacuum lines go that go out of the bottom of the heater/AC box assembly to the engine. One is gray and the other is purple. I've got a small round vacuum canister also that I don't remember the hookup for. HELP

 

[HAFROD]

OH YEAH, its a 78 Cutlass that came with a Chevy 305

 

[pontiacgp]

the purple one goes to manifold vacuum and the grey one goes to the heater valve

 

[HAFROD]

Do I need the small plastic round vac canister? I'm assuming now that the manifold vacuum goes to it and the purple or does the gray one go to it with another one going to the heater valve???

 

[pontiacgp]

my GP does not have a canister.

 

[darbysan]

The Vac Cannister is there to give constant vacuum source for HVAC and also for Cruise in some models. The purple line should be connected to the cannister, either directly or with a Tee. On mine, I have manifold vacuum , running through a check valve, to a tee, and then to the cannsiter. Some cannisters have 2 connections, some just one ( mine is the single type). If you have two connections on the cannsiter, one is vacuum in, the other is vacuum out to HVAC/Cruise.

If you don't like seeing the cannister in the engine bay, you can mount it just about anywhere. I mounted mine underneath the battery, on the bottom side of the fenderwell.

 

[HAFROD]

I don't have cruise control but what is HVAC?

 

[t01blaze]

Heating ventilation air conditioning