The only thing that resembles 'online chat' is the Live Chat box in the lower right corner of this/any page where you can talk to a PM rep directly.
Now, you've got to be online when they're online which is M-F 8am-4pm PST.
You'll see a 'chat box' where you can type your questions and start a chat. Sometimes, when the rep isn't available during those West Coast USA times, the chat box won't be there...but it returns soon.