heat barely works, used to have a/c. help needed.

yellowdartdave said

Incorrect.

It is a storage reservoir for engine vacuum that controls the heat and A/C system.

Keeps the vacuum operated doors in their desired location during low engine vacuum situations.ie full throttle,etc.

If it was a smog control device, why do only A/C A-Bodies have them?

Click to expand...

I think you're confusing a vacuum reservoir with the vacuum amplifier. The reservoir is just a tank that holds vacuum....the amplifier is a control assy for the EGR and related emission controls. You just need a good vacuum source to run the A/C dash controls. Most of the earlier cars just used a vacuum line straight off the intake but they found that on a long uphill run, there was insufficient vacuum to keep the system working properly, so they added the reservoir.