First to the comment "You set the TV to Cable not Air"
There are in fact several channel assignment schemes for cable, one for air, The AIR assignment (old analog days) is shared both sides of the border.
And in all cases Channel 3 is the same, be it cable, digital cable, different schems, or Antenna, channel 3 is the same.. So forget that one
That said. it is a logical suggestion
On the converters.. Unplug them for five minutes.. Then plug them back in
While you have them Turn them on THEN have the TV scan for channel 3 (Or manually set it to 3) NOTE that there are actually 3 of each channel (low/middle/high) so it might be best to scan if it does not lock in well
You should have the converter menu
Then try scanning
As I recall, Canada may not have fully gone digital yet... You MIGHT have set the analog bypass or manually bypassed the converters.. if you did that you will have to restore conversion.
But step one is to get the converter "Welcome" screen on the TV screen.
IF you are near St. Clair, MI.. I may be able to help you next week.. This week I'm kind of tied up here in the cardiac care ward dodging a heart attack. (Successfully it appears). (Well if it was not successful.. I'd not be typing now would I)