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Old 03-21-2012, 07:24 PM
Dufus Dufus is offline
Join Date: Feb 2011
Posts: 269
The air conditioning duct work in houses can make ticking sounds. In the winter, heated air causes the duct to expand along its length. When the heat cycles off, the duct slowly cools and retracts. Situation is reversed in the summer and it goes kcit, kcit, kcit instead of tick, tick, tick.