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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Heating / Air Conditioning System (Except HV, W/ Auto A/C) - Circuit Tests & Symptom Tests >> AIR CONDITIONING SYSTEM (for Gasoline Model with Automatic Air Conditioning System) >> PTC Heater Circuit [12/2019 - 11/2023] >> Description

PTC Heater Circuit [12/2019 - 11/2023]: Description

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

Symptom Factor
Heating performance is poor when it is cold.
  • Quick heater assembly malfunction
  • Air conditioning amplifier assembly malfunction
  • PTC HTR relays malfunction
  • Harness or connector
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