HVAC makes funny noises

My roommate and I have been the best of friends all our life. Therefore, I considered it a no-brainer allowing him to stay at my apartment when he needed a place to stay. Besides, Lord knows I really need help paying for it! Things went well during the first month or two of our housing arrangement. About six months in, though, things took an extreme turn for the worst. As strong of a connection as my bestie and I had produced throughout the years, all it took was my faulty HVAC unit to put a strain on us. The system ran rather well in the wintertime as the heat was just one aspect used during that time. The air conditioner was a different issue, however, and was the biggest reason behind my new roommate’s nervousness. Whenever the A/C was in operation, it would knock. The longer it was on, the louder the annoying tone. The unit’s issues weren’t, at all, new as they’d been happening since I moved into the apartment. It wasn’t that big of a deal to me, though, since I’d learned to cope by setting up fans or simply cracking the windows when my place got too hot and stuffy. Furthermore, I’m one that would rather be warmer, anyday. My friend was an alternative story as he liked to be in cooler temperatures, even during the winter, oddly enough. Since neither he nor I were able to afford a new system or simply fans that cooled to his heart’s desire, we were susceptible to the apartment management’s maintenance schedule and their willingness to repair the unit. After pestering them enough, they eventually sent some sort of tech to silence the maddening knocking.

HVAC unit