Overview:

AC0001-1799 Air Canada Mainline
AC1800-1899 Air Canada Vacation Scheduled Flights
AC1900-1949 Air Canada Vacation Charter Flights
AC1950-1999 Air Canada Cargo Flights
AC2000-2989 Air Canada Extra Section Flights

Breakdown:

AC0001 - 0099 Asia/Pacific/Israel/South America
AC0100 - 0299 Domestic (Canada - Mainly Central Western)
AC0300 - 0399 Transborder (USA)
AC0400 - 0499 Rapidair YOW/YUL
AC0500 - 0599 Transborder (USA)
AC0600 - 0699 Domestic (Canada - Mainly Maritimes)
AC0700 - 0799 Transborder (USA)
AC0800 - 0899 International (Europe)
AC0900 - 0999 Florida/Caribbean/South/Bahamas/Bermuda/Venezuela/Colombia
AC1000 - 1199 Domestic (Canada) & Transborder (USA)
AC1200 - 1299 Transborder (USA) & Points in Mexico (except MEX)
AC1800 - 1899 AC Vacations (Cuba, Dominican Republic, Grenada, etc)

There may be a few exceptions to the rule, but more or less, that's the list.