I have a vacuum hose on my 72 Polara 440 with A/C, it runs from heater control out through the firewall to the engine compartment, it runs along side the cable for the water control valve. Anyone know where it ties in? Service manual just says "go's to engine vacuum." Should there be a port on the intake manifold? I'm trying to keep it as close to factory as possible. Thanks.
Vacuum hose connection
- Thread starter polarus
- Start date
As a side note, what about the carb bowl vent line and the vac and purge lines on the carbon cannister?
Somewhere, in the FSM, I suspect there are vac hose routing illustrations for both the HVAC system and the emissions system too.
Typically, the vac source for the HVAC system is a vac tree on one of the rear intake manifold runners or a fitting on the power brake booster's main vac line, at the booster. In some cases, there might be a separate vac reservoir under the hood, where the HVAC vac goes first, before the vac goes to the control units. That additional reservoir can also have a check valve in it to prevent the a/c air from coming out of the floor and defroster vents during long periods of heavy throttle and lowered intake manifold vacuum.
Just some thoughts,
CBODY67
Somewhere, in the FSM, I suspect there are vac hose routing illustrations for both the HVAC system and the emissions system too.
Typically, the vac source for the HVAC system is a vac tree on one of the rear intake manifold runners or a fitting on the power brake booster's main vac line, at the booster. In some cases, there might be a separate vac reservoir under the hood, where the HVAC vac goes first, before the vac goes to the control units. That additional reservoir can also have a check valve in it to prevent the a/c air from coming out of the floor and defroster vents during long periods of heavy throttle and lowered intake manifold vacuum.
Just some thoughts,
CBODY67
3175375
Senior Member
It looks like the connection that goes to the vacuum reservoir. It looks like that hose runs back to the heater and air conditioning mode control switch on the dash. Look up the diagrams in the FSM.
It's a little confusing because you are showing the cannister for the evaporation system.
The green striped hose should plug into the vacuum port on the intake manifold that the power brake booster hose is attached to. It will look something like this:
It may have more or less spots for hoses to attach to. These are sometimes lost or discarded with engine swaps or rebuilds, so you may not have the correct vacuum fitting on the manifold.
The green striped hose should plug into the vacuum port on the intake manifold that the power brake booster hose is attached to. It will look something like this:
It may have more or less spots for hoses to attach to. These are sometimes lost or discarded with engine swaps or rebuilds, so you may not have the correct vacuum fitting on the manifold.
You're right Big_John, I was just trying to show the overall length of the hose, it's too small to fit on any of the ports on the canister which is evap. only as far as I know. Looks like I need to purchase a new fitting for my intake manifold. This is the only reference I could find in the FSM.
Last edited:
3175375
Senior Member
I am most certain that the hose goes to a vacuum reservoir. It’s not shown in the diagram of the interior.
3175375
Senior Member
See scrawling
That would be true IF there was a vacuum reservoir.
I double checked a '72 FSM and the only mention of a vacuum reservoir is in the Auto-Temp A/C system.
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