From your test results I get no feel for whats happening. You state: "Temperature Dial has no effect when vehicle is running, but works when vehicle is not." Describe how the temp dial works when not running. Does the heta go away?

Very little of what I expect to happen with changes in the temp wheel will work with the engine not running.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician