Did the test today on my setup and I actually found the reverse
happened. Setpoint of 3.0°C was reached with the fan blowing
down on to the heatsink...5 mins later all things the same, I couldn't
get the fan/peltier arrangement to reach setpoint.......
Same ambient, same 12V battery level, same setpoint etc.
so it seems that Leon's heatsink/fan shape possibly lends itself
for cooling efficiency to improve when reversed.
We should name this the ''Leon effect""
Steve