I have a schematic somewhere. I sat down one night and drew it up from a couple bum modules I have. There are a couple of custom integrated circuits which I cannot identify. But, of the ones that I have opened, all failed in the mechanical relay. It is not sealed which plays heck with the exposed mech relay. Contacts rust and coil windings corrode and break. Some are easy to fix.
Edit: Ooops ! Wrong module. I assumed the OP was talking about the fan delay relay, which I was talking about above