When electronics act up due to significant temperature differentials especially given a 33 year service life, I would suspect hairline fractures in the solder joints on the Climate control unit. Given its age, it would be time well spent to reflow the solder on any pins you can access. This also usually fixes many switch button related issues.

There are also some capacitors worth changing, I dont recall the specifics but it is well documented on the forum. If you need a few, PM me, when I did mine I had to purchase a 20 pack, so can spare a few.

Good luck

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1987 300TD 310K mi (Hans)
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