This fan switch might be more efficient?
http://216.122.237.122/cgi-bin/store/oracle.cgi?x=parts&show_details=148&s=contr\
ols&cur=USD
Fan on at 110F...off at 90F. Should not come on on warm spring days.
NOTE: Thru this series of posts there are some mistakes....some have been
corrected...some haven't. Basic ideas are sound though...just need to think
before applying them?