I believe the temperature controller is located above the passenger footwell. Do you have a copy of the factory service manual or more specifically, the schematic for your car? IIRC, yours has a small sampling fan that draws air across the sensor for better response to temp. changes. Also, the pushbutton controller was changed in 85 or 86 to a new version.

Another note, have you checked the fuses? The aluminum ones are notorious for causing intermittent problems. Use the copper ones if you can find them.

You might find someone in the Tech Help section of the forum that is more familiar with the nuances of the later 126 series climate controllers.

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Sam

84 300SD 350K+ miles ( Blue Belle )