When I bought my condo it came with two built in A/C units from York. They are super noisy, both the compressor outside on the balcony and the fan unit inside. Any tips on how to silence it, especially the one inside? Obviously I could rip it all out and put in a new one, but are there any easier/cheaper alternatives?

First thing to try is making sure the blower is clean. Dirt can unbalance it which creates vibrations.

And since you removed lots of sheet metal to clean everything, making sure the sheet metal is screwed on tight .. no screws missing.

Might be a good time to have a tech come out and clean inside and outside units, the fins as well .. and nag the heck out of him about those screws in the sheet metal.

I have 7 York split air systems...while the inside/evaporator units are as quite as most any other A/C, 2 of the outside/compressor units where very noisy sometimes...I fixed both. The problem on both was due to very close clearance between one piece of tubing on the inside and the outside case. I only had to very slightly bend the tubing away from the case just a few millimeters to stop the noise/rattle...I also put a small piece of cushion material around the tubing where it was touching the case before as added noise prevention...this fix changed the compressor unit from noisy to pretty quite...been fine since.

Regarding the inside/evaporator unit, if the squirrel cage type blower/fan assembly is dirty/got gunk on it, it can become noticeably noisy. Use a small paint bush or better yet a baby bottle cleaner brush to clean the the squirrel case fan assembly...and of course be sure the filters are clean.

Edited June 19, 201214 yr by Pib

Bearing can go bad on the inside units (had an LG that it happened twice before got fed up with it and replaced the fan coil unit). If maintenance can not reduce noise replacement units can be used - matching to the outside compressor size it does not have to be the same company. We replaced the LG inside unit with fuji-Air (which appears to be a Mitsubishi) for a much quieter experience.