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DTC B1423/23: PRESSURE SWITCH CIRCUIT Lexus LS III

Automatic HVAC System ~169 words
  1. Remove A/C ECU, leaving harness connectors connected. See «A/C ELECTRONIC CONTROL UNIT»(ref-99101-S36801596042001061800000) under REMOVAL & INSTALLATION. Install manifold gauge set. Turn ignition on.
  2. Backprobe A/C ECU connectors between terminals A12-17 (Blue/Orange wire) and A13-12 (Light Green wire). (Схема №8) See «WIRING DIAGRAMS»(ref-99101-S32973477022001061800000). Turn ignition on. Voltage will vary depending on refrigerant pressure. Voltage should be about 4.8 volts with refrigerant pressure at 462.7 psi (32.5 kg/cm 2 ), about one volt with refrigerant pressure at 56.6 psi (4.0 kg/cm 2 ) and 0.1-0.5 volt with refrigerant pressure at zero psi (zero kg/cm 2 ). If voltage is as specified, no problem is indicated at this time.
  3. If voltage is not as specified, test pressure switch. See «PRESSURE SWITCH»(ref-99101-S42304802972001061800000) under COMPONENT TESTS. If switch is okay, go to next step. Replace pressure switch as necessary.
  4. Check wiring harness and connectors between pressure switch and A/C ECU. Repair as necessary. If wiring harness and connectors are okay, temporarily substitute a known-good A/C ECU, then retest system.

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