Rick's Free Auto Repair Advice

Toyota AC light flashing

Toyota AC light flashing, AC doesn’t work

If the AC doesn’t work or your AC light is flashing on your Toyota, the problem may not be as bad as you think. Toyota AC compressor clutches use a lock sensor circuit to make sure the clutch is fully locked-up to the compressor when the AC is on. The lock sensor generates an AC voltage as the clutch turns and sends that signal to either an A/C amplifier or ECM (depending on the car model). The signal is compared to engine RPM and that’s how the system knows that some slipping is happening.

So the problem can be caused by an actual slipping condition in the serpentine belt or the clutch. So check that first. If the belt is slipping, chances are you have a weak belt tensioner. But if you don’t detect any slipping in either the belt or the clutch, the problem may be a bad lock sensor, or a broken lock sensor wire. If you replace the sensor, make sure the magnetic pickup inside the compressor is still in place. Sometimes they can fall out.

© 2012 Rick Muscoplat

Posted on by Rick Muscoplat

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