i think that would be a real problem if the thermostat were closed. that thread i pointed out indicated that it should be fixed open. i've also read somewhere that holes should be drilled so that there is always some flow to the main. i still believe this setup is only suitable for really warm climates.
i think the electric conversion is worth doing as long as you get it working right. after all, the newer models have this setup now...
1993 300e-2.8 - gone now <sigh>
"Do not adjust your mind, it's reality that's malfunctioning"