I think your CCU circuit board is probably the same an 1989 420 SEL CCU board. Can you tell me how you were able to remove the circuit board from the case? I have removed the bottom plastic cover on the CCU, and pulled the pin from the temp. control wheel but the pushbuttons seem to be retaining the circuit board in the case. How would one disconnect the pushbuttons from the circuit board and is there anything else that is retaining the board in the case?

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1989 420 SEL