Marty or pearl I was looking at this heater problem from a year ago http://www.justanswer.com/mercedes/8wia0-mercedes-560sl
-1987-mercedes-560sl-heat-intermittant.html and I am having the exact same problem. no heat in any control position with engine running, shut the engine off and turn key on and it has full heat until the engine cools down heat. All of the same items have been checked. blockage. proper electrical operation, aux pump runs. Thermostat, replaced, everything is exactly the same as this article. It doesn't look like it was ever solved I also saw another case at this site
JA: Is the car in "Park" or "Neutral?" Do you know if your car has a "wheel lock" feature?
Customer: I'm sorry Pearl this is a 1987 560 SL what in the world is a wheel lock feature
JA: Are you fixing your SL yourself? What have you tried so far?
Customer: Everything in this posting a year ago http://www.justanswer.com/mercedes/8wia0-mercedes-560sl-1987-mercedes-560sl-heat-intermittant.html
JA: Anything else you want the mechanic to know before I connect you?
Customer: I'll be a minute Sorry