Here is the original item:
My appliances are always hungry.
(A) For example,
the dryer will eat underwear,
(B) and the
microwave will suck off half a frozen
dinner (C)
while it is cooking.
You wanted to do this:
My appliances are always hungry. For example, the dryer will eat underwear,
and the microwave will suck off half a frozen dinner,
while it is cooking.
Adding a comma after dinner is an error. While it is cooking is a subordinate clause. When you connect a subordinate clause to the main clause in front, you rarely use punctuation.
You might want to review the rules.