Chat support is available Monday to Thursday 9AM-7PM EST and Friday 10AM-5PM EST, but only for paid accounts. Within those hours, you can chat with a support representative by clicking the Support button.
Outside of those times, the Support button will not appear.
If the chat button isn't appearing within those hours, and you're logged into a paid account, try refreshing your screen. If that doesn't work, try clearing your cookies then clearing your cache. Failing that, try a different browser.