Is it possible you have a flow restriction to your cooler somewhere? The rotaxowner forums have some information about that. Roger Lee has some suggestions.

It doesn't surprise me that they get warm in an extended climb, but it seems strange they don't drop very quickly when you push over into cruise. I can hit 240 in an aggressive climb, but it comes down to where the thermostat is regulating within ~15seconds of pushing the nose into a less aggressive climb.

Phil, what MAP and airspeed are you climbing at?