I know this has been asked before and I have read the responses. I have a condo with the air handler in a closet and a direct return air vent at the floor and the unit mounted about 25" inches off the floor. There in no mechanical problem, however, when the unit turns on it is way too noisy. It seems the answers in the past revolved around getting more air by creating another intake vent or by placing a baffle between the filter and the fan. Can anyone give me a description of what the baffle should look like so that I can try it. My filter/ return opening is 20"X20". Any help would be greatly appreciated. If there is another answer, p;ease don't hesitate to suggest it. I am open to any ideas.

In my opinion, and please have an expert verify this, a baffle would not be a viable idea. The last thing you want to do is block the air flow of a furnace return. It can create all kinds of problems with both heating and cooling cycles, just like a plugged filter can. Some acoustical lining may be available if there is any ductwork between the air handler and the actual vent which may help the noise... like a muffler. But any baffle could restrict air flow and that is not a good idea.

Vibration pads can be installed under the air handler. That platform is probably not very solid and it's almost acting like a speaker, amplifying the movement.

I'd suggest a Unistrut platform with vibration isolators.

Baffles would only help air noise, which I doubt your having.

I'd be interested in seeing the setup. Post a pic using "Go advanced"