Mitchell Toyota Mitchell Figure 9: Deciphering Toyota (Denso) Compressor Schematics: Unless you've been through factory Toyota or Lexus training, you might be confused by the schematic circuit titles listed in both aftermarket and factory diagrams. There are 3 connectors on this Toyota compressor: 1.) Refrigerant flow (5-volt ref, ref low (sensor ground) and flow signal), 2.) Variable displacement solenoid ground and 12-volt PWM control, and 3.) Compressor speed (a.k.a. " Lock " ), ref low (ground) and clutch control (12-volts). Figure 10: Toyota HVAC Amplifier " Lock " ?: The light blue wire titled " LOCK " on the schematic for this 2013 Camry's HVAC amplifier (control module) turns pink and then blue as it goes through various connections prior to terminating at the compressor clutch connector's " SSR + " terminal. The apparent ambiguity without some insider knowledge could lead to an easy misdiagnosis. Figure 11: Toyota's DTC chart for B1422 Compressor Lock Circuit shows the waveform that should be coming out of a running compressor. The chart specifies that the compressor speed should have no more than a 20% deviation when calculated to what it should be based on engine RPMs. DTC will be accompanied by a blinking compressor light on the HVAC control head. the engine is running, and the compressor is commanded off. If the sensor is working properly, the system has the correct charge and the compressor is running, the sensor voltage will display around 1.0 - 2.5 volts on the scan tool. Very little is written up on this sensor's operation or what the correct voltages should be in the service manual. displayed 3.65 volts. The tech then connected power to the clutch circuit with a jumper wire and the compressor engaged / vehicle's A/C cooled down. This tech was able to compare to another van of the same model year and the sensor read just over 4-volts with the engine running and A/C clutch off. The same data PID came down to 2.5 volts once the clutch was commanded on. An online post for this problem came up back in 2018 on a 2011 Sienna. The post stated that his customer's Sienna compressor clutch would not engage by itself nor would it engage when the clutch was requested to operate via a bi-directional scan tool request. The sensor flow voltage PID May 2021 One of the posters assisting the technician working on this Sienna had the same " no compressor clutch command w/B1479 DTC " on a 2013 Toyota RAV4 he had worked on previously. The RAV4 compressor would not come 6 MACS Service Reports