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Toyota Service
Toyota Service, Toyota Expert
Category: Toyota
Satisfied Customers: 4597
Experience:  30+ Yrs of auto experience, Award Winning Svc. Manager; Just Answer Customer's Choice Award Winner
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Interior a/c light flashing

Customer Question

interior a/c light flashing
Submitted: 3 months ago.
Category: Toyota
Expert:  Toyota Service replied 3 months ago.

Hello. Welcome to Just Answer. Please allow me to assist you. The number one cause of the AC light flashing (and intermittent AC operation) is due to a failure of the sensor that tells the AC unit the speed of the AC compressor when it is engaged and turning. If the sensor fails, of of the compressor has an internal problem, the RPM signal is either not sent or is incorrect. This causes the AC magnet clutch relay to disengage, and power is cut to the compressor. The effect of the loss of the RPM signal is the flashing of the light (this is what the AC unit does to shut down the AC magnet clutch relay. There are two types of rpm sensors; one you can replace, the other is replacement of the compressor. The only way to test the integrity of the RPM sensor is via an oscilloscope. If you do not have this electronic diagnostic tool, you will need to take the car to a professional shop where they have one to test the RPM signal.

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