Vacuum headache

[Reddtahoe2000]

Hello, new here. I have a 2000 chevy tahoe z71 with the 350ci engine. Cant find online any of the vacuum line diagrams. While underway, the recirculation door for the hvac will just periodically open and close depending on throttle setting. I have recently added a ford vacuum pump and 1970s vac canister to help out, but this has not fixed anything yet. The one the I isolated was on the driver's side, ran across the top of the block and then ducks into the firewall near the a/c dryer. Are there any other lines that run this system?

Thanks

Reddtahoe

 

[east302]

The recirc damper uses an electric actuator - it is tucked up in there and not the easiest to get to. It’ll look like the one to the right of the gas pedal. The plastic gears in it may just be broken and allowing outside air to push it around or not allowing the damper to set based on the signal from the control panel.

The hard vacuum line (#20 below) from the PCV fitting goes across the intake to a solenoid on the firewall near the accumulator. A second vacuum line (#14) goes from that to the water valve fitting on the heater hoses. When the “max” detent is set on the a/c temperature dial, the solenoid applies vacuum to that water valve, closing off the heater lines to maximize a/c performance.

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[someotherguy]

Excellent reply. I was going to say, there are very, very few vacuum lines on a Vortec small block.

There's no need for addition of a vacuum pump or reservoir setup on your truck.

Richard