I used to rent a room from a friend. He just had the central air furnace replaced due to a cracked exchanger. It was a 3 bedroom house with kitchen, living room. I capped the vent because I had lots of electronic equipment in the room. Now that I've moved out he claims that my blocking the vent cause the exchanger to crack and ruin it. Is that even likely?

The old leaky 20-year old duct work was not even fixed when the furnace was replaced so I'm quite doubtful of his claim.

Thank you.