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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) >> PTC Heater Circuit [11/2021 - ] >> Description

PTC Heater Circuit [11/2021 - ]: Description

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The air conditioning amplifier assembly sends operation signals to the PTC heater relays when PTC heater (quick heater assembly) operation conditions are met. Based on the signals from the air conditioning amplifier assembly, the PTC heater relays turn on, and power is supplied to the PTC heater (quick heater assembly) installed in the air conditioning radiator assembly.

HINT: 

If the heating performance is poor when it is cold, the following factors may be the cause.

Malfunction Status Factor
Heating performance is poor when it is cold
  • PTC heater (quick heater assembly) malfunction
  • Air conditioning amplifier assembly malfunction
  • Harness and connector
  • PTC heater relays