That sounds a bit high - they should be nicely snug but not overly tightened. The idea is to compress the gasket a little but not to squeeze it flat or cause it to squish out the sides. If the a/c manufacturer doesn't provide a torque spec, "snug" is about as definitive as it gets.
Check the tightness again after the first trip and again in another month. The bolts sometimes loosen up a bit.