If you can't find a schematic of the board, then you may have to.do this next bit. Do it CAREFULLY!! You'll have to remove the unit from the outer casing and set somewhere like a table where you can plug it in and test. When calling for n cooling what is running? Fan motor? Compressor? I believe you said compressor wasn't running. Check and see is it getting power? Is the capacitor good? There should be a value on the side of the capacitor. Check and see if it is within 3% of that number. If not, replace it. Capacitors, relays, and contactors are a much more common failure point than a compressor.