PT Cruiser, 2001 - 2005

Idle Air Control (IAC) Motor


Description & Operation

The Idle Air Control (IAC) motor is mounted on the throttle body. The PCM operates the idle air control motor.

The PCM adjusts engine idle speed through the idle air control motor to compensate for engine load, coolant temperature or barometric pressure changes. The throttle body has an air bypass passage that provides air for the engine during closed throttle idle. The idle air control motor pintle protrudes into the air bypass passage and regulates the airflow through it.

The PCM adjusts engine idle speed by moving the IAC motor pintle in and out of the bypass passage. The adjustments are based on received PCM inputs. The inputs are from the throttle position sensor, crankshaft position sensor, coolant temperature sensor, MAP sensor, vehicle speed sensor and various switch operations (brake, park/neutral, A/C).

When engine rpm is above idle speed, the IAC is used for the following functions:

Off-idle dashpot
Deceleration air flow control
A/C compressor load control (also opens the passage slightly before the compressor is engaged so that the engine rpm does not dip down when the compressor engages)

Target idle is determined by the following inputs:

Gear position
ECT Sensor
Battery voltage
Ambient/Battery Temperature Sensor
MAP Sensor

Removal & Installation

  1. Remove the air cleaner lid, disconnect the inlet air temperature sensor and makeup air hose.
  3. Remove the negative battery cable.
  5. Disconnect electrical connector from idle air control motor.
  7. Remove idle air control motor mounting screws.
  9. Remove idle air control motor. Ensure O-ring is removed with the motor.

To install:

The new idle air control motor requires a new O-ring. If pintle measures more than 1 inch (25 mm) it must be retracted. Use the scan tool AIS Motor Open/Close Test to retract the pintle (battery must be connected).

  1. Carefully place idle air control motor into throttle body.
  3. Install mounting screws. Tighten screws to: 6.2 Nm (55 inch lbs.) torque.
  5. Attach electrical connectors to idle air control motor.
  7. Install the negative battery cable.
  9. Install the air cleaner lid, connect the inlet air temperature sensor and makeup air hose.

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