H2 Tags?

You have a completely different problem: you don’t have an h1 heading. It should contain the relevant keywords for the page you are currently viewing, which should also appear in the page title. You don’t need an h2 as long as you don’t have an h1.

On the homepage I would recommend to describe your offer in the h1, I guess something like “Replacement Compressor Parts”. On the product archives, the h1 should contain the title of the accessed category. At least on the product detail pages you have an h1 – very good.

How you complete these missing headings depends primarily on your templates, which I don’t know.