Sounds like these are double glass thermopane sliders which have suffered a seal failure.
The glass units are two panes with an air gap and a separator seal strip around the outside. The air gap is usually filled with dry argon gas, but if a leak develops then as the window heats and cools moist air is drawn in and out creating the moisture fogging on the inside. When it gets really bad you will actually see little water droplets.
Have you checked with the installer and manufacturer, there is usually a warranty on seal failures. For windows its usually 10 years or more, not sure about sliding doors in a rental unit, might be much shorter.
I've never heard of cleaning and resealing a thermopane unit.
In any case you shouldn't have to replace the whole door unit frame and all, just have a local window and door installer replace the glass in the original frame for the section that has failed. I've had this done before, sealed glass pane might be around $250 plus labor for the frame disassembly and re-assembly.
I don't work for Stockcharts, I'm just another user always trying to learn more and willing to share what I've already learned.
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