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Toyota Service
Toyota Service, Toyota Expert
Category: Toyota
Satisfied Customers: 4944
Experience:  30+ Yrs of auto experience, Award Winning Svc. Manager; Just Answer Customer's Choice Award Winner
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I have 2005 Tacoma truck in which the AC light flashes

Resolved Question:

I have 2005 Tacoma truck in which the AC light flashes within seconds of turning on the AC system. I had the refrigerant tested and it is 100% R134a. The compressor turns over by hand easily, there is a charge in the system as it had 90PSI yesterday with an outside temperature of about 80 Degrees F. There is no tag on the rad support indicating the proper charge and I was wondering if you might be able to also tell us that
Submitted: 5 years ago.
Category: Toyota
Expert:  Toyota Service replied 5 years ago.
Toyota Service : Hello. Welcome to Just Answer. Please allow me to assist you.
Toyota Service : Hi.
Toyota Service : Is the vehicle available?

No, it is at our sons place at present.

Toyota Service : Ok
Toyota Service : There are two main causes for the AC light to flash, neither of them include freon charge

LAst night I insatlled a set of AC gauges and that is when i found the pressure in the system. I alos tested the Refrigerant and found it was 100% R134A

Toyota Service : The most common cause is a failed compressor RPM sensor, the other is a bad compressor clutch relay

Where do i find the compressor clutch relay?

Toyota Service : It is labeled "MG CL" or " MG CLUTCH" in the relay box under the hood

How can i test the RPM sensor?


Is there any way to test the relay by jumping out the terminals?

Toyota Service : The RPM sensor is located on the side of the compressor.

How can I test the RPM sensor?

Toyota Service : You can take the relay apart, and manually trigger the contacts, if they are not clicking together when the AC button is depressed

You can hear the clutch come on momentarily and then it realses and the flashing light comes on

Toyota Service : If the light continues to flash, the RPM sensor is not transmitting the compressor speed to the AC amplifier
Toyota Service : I am inclined to believe the RPM sensor is bad

I will see how i can change the sensor and see if that makes any difference.

Toyota Service and other Toyota Specialists are ready to help you