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

cudamark said
The vacuum amplifier under the hood is for smog control.....not heater.

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?