Air conditioning won't stay on when it's very hot out

I bought this ac about a month ago and it has been working great until today, the hottest day of the year. I have the ac turned on ac mode and the fan turned up. The hose is installed right, not bent or obstructed. I set the temp down to 70. I cleaned the filters and emptied the water. But ac still only comes on for at most 2 min then there is a thump noise and it turns off leaving only the fan going. Then after about 5 min the ac comes on then turns off again. It's been doing this for the last hour and I don't know what to do. I'm miserable and hot and drenched in sweat. It's 98 degrees out at the moment. I've tried everything I can think of. I thought maybe it has overheated so I turned it off for half an hour but made no difference. I can't afford a new ac already but it's looking like I'm going to have to buy one. I'm updating my review the day after I posted it. As soon as the outdoor temperature started going down the unit was able to stay on for longer periods of time. As soon as it was back in the 80s instead of hovering around 100 I stopped having problems and the unit has worked fine since. I assume it was just to much for it to cool the space it previously had no trouble with once it became dangerously hot out. I don't expect many more days that hot but am going ahead and getting a second unit of some type just in case. I changed my rating from 1 to 3 stars.

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