IronDoc,
This is a tough problem. A LOR from your program director may not be required but it is usually understood that applicants will have one--questions will be raised if there is not one. On the other hand, you should never turn in an LOR if you are unsure of what it says.
I don't mean that you should read it (that's either illegal or dishonest if you sign the form saying you won't), but it's perfectly fair to ask the letter writer about the general flavor of the letter. If the chairman says he barely knows you and can't write a strong letter, you should be able to fix that. If he says he thinks you are a tool and the letter goes on and on about your toolness, try and find someone who thinks otherwise and get them to write a strong letter.