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Compressor Circuit

WARNING: This page is about a different car, the 2001 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
  1. Remove A/C control assembly, leaving harness connectors connected. See A/C CONTROL ASSEMBLY  under REMOVAL & INSTALLATION. Start engine. Push AUTO switch. Measure voltage between connector A8 terminal No. 10 (Light Green/Red wire) and ground. If less than .7 volts are present with switch on, and battery voltage is present with switch off, go to step  4. If voltage is not to specification, go to next step.
  2. Remove clutch relay from engine room junction block. Check relay. See RELAYS  under component tests. Replace relay as necessary. If relay is okay, go to next step.
  3. Disconnect compressor clutch 4-pin connector. Connect battery voltage to connector terminal No. 1 (Black/Blue wire). Connect negative terminal to ground. If clutch does not operate, replace clutch. If clutch operates, repair wiring between compressor clutch, relay and A/C control assembly.
  4. With ignition on, measure voltage between A/C control assembly connector A8 terminal No. 5 and ground. If battery voltage is present, go to next step. If battery voltage is not present, replace engine ECM located behind right kick panel. See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
  5. Start engine. Push AUTO button. Measure voltage between connector A8 terminal No. 10 and ground. With clutch activated, battery voltage should be present. With clutch not activated, less than one volt should be present. If voltages are to specification, check wiring between clutch relay and A/C control assembly. If voltages are not to specification, replace A/C control assembly.
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