The light green wire should be going to the high pressure switch, which has to be closed for the AC demand signal to make it to the AC demand input on the PCM. Both the low pressure cutout (compressor mounted) and the clutch cycling switch (accumulator mounted) have to be closed and allowing the signal from the ECM to be pulled to ground for the dark green and white AC relay control wire to be grounded and engage the relay. If you can ground the cycling switch and the compressor cycles, then the high pressure cutout and low pressure cutout are good and you have either a faulty cycling switch, bad ground on the cycling switch circuit, or system pressure is too low for the switch to close. Diagrams I'm using for reference are attached.
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