Problem: My furnace wobbles and shakes sometimes. What could be the problem?
Answer: Most of the time wobbling inside the furnace is caused by the blower wheel being out of balance. Most of the time a piece of something (filter, furnace insulation, paper, dirt) has become sucked in the blower wheel (squirrel cage) and causes it to become off balance and wobble. I would recommend turning off the power to the furnace, taking the blower door off and inspecting the blower wheel with a flash light and a mirror. Sometimes the blower wheel balance weights can fall off and this will also cause the blower wheel wobble. Many times it is hard finding the weights and where they should be place if they have fallen off. Sometimes is almost better to replace the whole blower wheel if the weights have fallen off. The weights are one or two are little pieces of U shaped metal that friction fit on to the blower wheel fins. A motor with the bearings going out can also cause wobble, but most of the time it is the blower wheel out of balance that causes wobble. Below we have a really good YouTube video made by HVAC in SC which shows how to clean a blower wheel. Thanks so much for this informative video!