My heater controls do not open and close the door in the system anymore. They were working fine until I had the core replaced (again) a few weeks ago. It was a warrantee deal this time so I took it back to Dobbs and the guy doesn't seem to believe me that it worked when I dropped it off. Long story short...I was told that the part is no longer available - the solenoid, that is. Is he telling me the truth or just being a jacka$$?