Here is the item again:
Although fans blew in every room, (A)
Faye found the house unbearably
hot. (B)
And wished that the air conditioning repairman,
(C) who was already three
hours late, would pull into her driveway.
You correctly realized that the period after hot created a fragment. And wished that ... is a lonely verb phrase, so it cannot stand alone as a complete sentence.
To fix this fragment, you chose to do this:
Although fans blew in every room, Faye found the house unbearably
hot and wished that the air conditioning
repairman, who was already three hours late, would pull into her driveway.
You have correctly employed Punctuation Rule 8:
Main clause + Ø + lonely verb.
Rock on!