1990 Lumina Climate Control

The climate control stopped working the other day. It stopped working but then it would start again once in a while then finally it stopped completly. Neither the heat or the AC work. Where do you think I should start to look? Are there any known problems for luminas in this area?

I have not had the problem myself, but have read here that it might be the vacuum lines, start with the storage ball under the front left fender and trace them to the engine, sometimes the old rubber tubing will dry out and can't maintain the vacuum. Which is needed for the heater controls to work. Hope this helps