Inexpensive Fix
While I would prefer the Vans shutter (I would have the cable control attached to the engine frame with the adjustment knob accessible thru the oil door,rather than in the cabin), I fabricated a plate from .060 aluminum sheet to attach to the back of the cooler. This plate is easily attached by using one of the long fasteners already holding the cooler, and a second that attaches to the middle hole already in the cooler flange on the opposite side. For the front side of the cooler, I cut strips of aluminum tape and insert these as far a possible between the cooler and the cylinder head. The adhesive holds the tape in place on the face of the cooler. Our weather in Michigan is not so different than Berlin. I find covering both sides is necessary to achieve about 170 Fahrenheit on the coldest days. Typically, I put the tape and plate on about end of October, and remove in April. This has been working well for since my first flight in the 9A in 2004.
Terry Kohler, CFI
RV9A N323TP