Window air condition unit makes obnoxious buzzing sound about every minute...?

We just bought a 10,000 btu window unit off craigslist for only $25. It was sold as a 'working' unit. We plugged it in and set it up yesterday and it worked okay for about 30 minutes but didn't really cool the room. And then it started making a really loud and obnoxious buzzing sound (for about 2 seconds) every minute or so. Plus the lights will flicker when that buzzing sound occurs.

Could it be that 10,000 btus are too much for the circuits (or power outlet) to handle or something thus the flickering lights? Before this 10,000 unit we had a 5000 unit set up that didn't seem to do a great job of cooling but at least didn't make that horrible racket... Last year at my old apt, I remember the power on one side of the apt went out after I plugged my hair dryer in and turned it on. And we were using window units at the time as well. The landlord chalked it up to too much power being utilized and said to turn the big window unit off when using another heat bearing electrical appliance...

Window air condition unit makes obnoxious buzzing sound about every minute...?

you might have a bad compressor,before you chunk it do this:

go into the unit and check the wires going into the top of the compressor and look at the overload on top of the compressor , it may be the problem! if it is discolored or smells burned or has a loose wire coming out of it then replace it. It also may be the start capacitor(leaky/swelled up)

you can buy a capacitor assist called a hard start device. and that may bring the compressor on line. But remember this..any air conditioner that sells for 25 bucks is not going to be a bargain.

Window air condition unit makes obnoxious buzzing sound about every minute...?

I think you have been snookered with a bad compressor.

One other possbility is a bad starting capacitor.

Unless you know someone who works cheap, the repair could total the cost of a new window unit.