I have a central air conditioning unit installed in my backyard. As my backyard is tiny, and the unit is somewhat big and clunky, I am looking to build (the smallest possible) vented, wooden cover over top that can be left on year round. How much space would I need to leave on the sides/top to ensure the system doesn't burn out or worse?
Majority of manufacturers call for a minimum clearance of 36" above and under no circumstances should any a/c be enclosed on all 4 sides. If enclosed on 3 (not recommended) youd want at a very minimum 2 1/2'. Enclosing your a/c will not only put ultimately lead to the failure of your compressor which will be void of any warranty your efficiency will drop to near zero and your condensers ability to reject heat will be severely impaired. 10/10 would not recommend what you're proposing.
Have you considered replacing with a horizontal discharge a/c they occupy much less real estate and are often used in spaces with limited area ie condo balconies etc.
Also new condensers are a lot quieter & nicer aesthetically than their predecessors.
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