I live in a condo unit and the kitchen sink has been unable to drain for the past 2 weeks. I've tried to unclong more than a dozen times with regular plunger and it hasn't fixed the problem. I've added baking soda and vinegar, nothing, poured the chemical pipe decloggers, nothing, used a wet dry vacuum to apply suction, nothing, using a high pressure plugger, nothing. Worth noting about a year ago the kitchen sink was clogged and similarly struggled then to unclog it. Plumber came, snaked it, didn't work, then cut the pipe open downstream of the P-trap and still couldn't determine what the problem was. A few days later though, building management brought up some construction vacuum and that did the trick. Which is why I'm thinking the pipe might be airlocked as I'm pretty sure my sink doesn't have an air exit valve.