Joe,
I can't answer your question, but I know someone who can. They are on the Discovery Owners Forum. If you are not a member of DOAI it is a must for Discovery owners. You will get advice on any issue you might have. Go to the Discovery owners association site and sign up. Then go to the forum and post your issue. Sometimes you will get a response within minutes. I am assuming your unit is a Norcold. I have attached a Norcold-Troubleshooting-Manual. Hope this helps.
Jim Pinkerton