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Home >> Lexus >> 2025 >> NX 350h >> Repair and Diagnosis >> External Pages >> Different car >> Section 71 (Heating / Air Conditioning System - Diagnostic Codes, Circuit Tests & Symptom Tests) >> AIR CONDITIONING SYSTEM (for Gasoline Model) >> Heater Water Pump Circuit [11/2021 - ] >> Description

Heater Water Pump Circuit [11/2021 - ]: Description

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The heater water pump assembly supplies engine coolant to the heater radiator unit sub-assembly to prevent a decrease in the effectiveness of the heater.

According to signals from the air conditioning amplifier assembly, the semiconductor power integration ECU operates the heater water pump assembly.

Malfunction Status Factor
  • No warm air comes out (Blower control is normal)
  • Outlet air temperature does not increase (Blower control is normal)
  • Temperature of outlet air is warmer on left or right side (When same temperature set for both sides)
  1. Semiconductor power integration ECU malfunction
  2. Heater water pump assembly malfunction
  3. Air conditioning amplifier assembly malfunction
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