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Discussion Starter · #1 · (Edited)
I've been googling this for weeks and have read tons of threads about it and the only one that had exactly my issue didn't have a resolution so let me start with symptoms and what I've tried.
2000 Sienna manual AC
Bought the car a couple months ago and when I press the AC button the compressor engages for a few seconds then light starts flashing and disengages. If I keep toggling it on and off every time it blinks it will actually get cold. Radiator fan turns on successfully when compressor engages.

Started with replacing the belt since it was worn and slipping. Unplugged the battery for a while to reset after this replacement.
Took out the AC control module and inspected for any signs of corrosion or bad parts. Looks clean with no signs of bad components blown caps etc.
Checked stall sensor with engine off, resistance within spec.
Checked pressure sensor. Continuity across one set of pins and none across the others. Found conflicting data on which set of pins are which so this could still be a culprit but as I understand it if I see continuity I'm good and the other set of pins related to the fan turning on or something.
Rented an AC manifold gauge. Low side would start around 40 then dip down to 30 or 20 before turning off. High side around 100. Added refrigerant until high side was at about 200 and low side still around 40 when AC engages.
Viewing window on drier has fluid and bubbles moving through it when compressor is engaged.

I tend to think it's not the compressor since it is not locked up and will still get cool if switch is toggled. I assume some sensor/wiring is either bad or something is actually wrong that I'm not thinking of that is causing the computer to turn off the compressor.

This model doesn't have the AC relay that often goes bad on the models that have auto AC. The relay is built into the computer and since the compressor clutch is engaging I assume the relay is not bad.

Have never worked on AC before so lemme know what I missed, thanks!
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