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2009 ES350 Ventilated Seats

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Let’s troubleshoot this issue:

  1. Compressor Clutch Engagement: Physically verify if the compressor clutch engages when you turn on the AC. Sometimes, even if you hear a click, it might not engage fully.

  2. Sight Glass Inspection: Check the sight glass behind the driver’s side headlight (if you don’t have a gauge manifold set). You should see a clear stream of fluid with minimal to no bubbles. Bubbles indicate an issue with the refrigerant charge.

  3. Evaporator Lines: Verify that the line going to the evaporator is cold and the return line is warm when the AC is running (right at the firewall). This confirms proper cooling.

  4. Air Mix Servo: Ensure that the air mix servo is sweeping its full range based on the dial selection. This affects the blend of hot and cold air.

  5. Radiator Fans: Check if the radiator fans come on at low speed when the AC is engaged. They should stay on during AC operation.

  6. Dryer and Expansion Valve: If you opened the system, consider replacing the dryer and expansion valve/orifice tube. These components should be replaced when the AC system is opened.

Additionally, if you notice any abnormal sounds or reduced air flow, a worn-out blower motor could be the culprit. I recommend having a professional technician inspect your AC system to diagnose and address the issue effectively. 


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Thank you, RX400h. But I was looking for info re: front seat ventilation, thus the title of the post. But it is great to see an accurate (I’m a retired AC technician) description of correct troubleshooting of an automotive AC system! With this heat wave upon us, no doubt your words of wisdom will fall on needy ears at just the right time!

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Sorry, Don. How about these suggestions?

  1. Fan or Wiring Issues: Ventilated seats rely on small fans built into the seat and backrest to circulate cool air. If these fans become jammed or fail over time, it can result in weak airflow. Additionally, check the wiring connecting the fan to the power supply – any damage or disconnection could be the culprit.

  2. Seat Control Module: In some cases, a malfunctioning seat control module can cause the entire system to stop working. This module regulates fan speed and direction, so if it’s faulty, the ventilated seats won’t function properly


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