heater won't turn off

I just got registered and have looked around the site a bit, enough to think I'm really not at the right place for what I need.  But I'm in this deep so I'm gonna go ahead and ask my question anyway.  My problem is in the ballpark at least.  I have a 1994 Lincoln Town Car and yesterday the heater fan decided it would not turn off.  No matter what I do.  The led indications work normally as far as increasing and decreasing the temp and changing from floor to ac to defrost or vent whatever.  And when I push the OFF button, it says OFF, but the fan is still blowing away. I'm thinking maybe there's a set of relay contacts stuck together somewhere or the output logic that controls that relay is stuck in the on state.  But I don't know where anything is physically on this car nor do I have a schematic -- so I could use some help.   I sure would appreciate any advice/suggestions or comments anybody might have. Thanks! 

I would get a service manual of some sort for it with wiring diagrams!