Mazda (CX-9) TSB: AC Poor Performance due to defective Outside Temp Sensor

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ASH8
This applies to cars with FULL Automatic AC (Air Conditioning) Only.

Mazda in North America has released a bulletin to all Mazda Dealers informing them of an issue with owners complaining of poor AC performance which has actually been around for sometime on multiple models over many years.

The small external Sensor located behind Front Bumper can be out by as much as 50 degrees Fahrenheit or 10 degrees Celsius (under reading) meaning Temperatures outside of car are physically way hotter than what the instrument reading (from Sensor) says it is resulting in the cars AC's not cooling down inside cabin as it should.

Personally I know many owners who have had issues with Mazda's poor AC performance, I trust this finally fixes the problem.

The supplier of the Sensor part to Mazda has rectified the issue with their parts manufacturing process.

Bulletin now applies to Europe and UK, therefore the rest of Mazda world.
In almost all cases if Sensor is determined to be defective the Front Bumper must be removed to access and renew Sensor, also depending on the car specifications the Radar and Cruise Control Sensors etc may require Dealer to re-aim them, We suggest Dealer has adequate NEW Sensors in parts stock so rectification can be performed on the same day.

Note: Not All cars with this sensor has defective Temp Sensor units, only those found to be incorrectly reading outside ambient temperatures will be renewed while still under normal new car warranty.

This is Not a Recall.


See the .Pdf Attached. with more details.
Normal Warranty Period Applies...
 

Attachments

  • AC Sensor.pdf
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  • AC Sensor Europe TSB-R115-22.pdf
    700.8 KB · Views: 117
Not sure if this to apply unless if your external temperature displayed in the car is also wrong. Although the TSB says « poor AC performance OR wrong temperature displayed »

But if the temperature displayed is correct and the AC is weak, this may not be the fix.

« Some Mazda owners may complain that the outside temperature reading on the instrument cluster is displayed more than 50 °F (or 10 °C) lower »

Here is the North American complete TSB:
 
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I agree with youri. My display is accurate, and the AC still seems inadequate for a cabin with that much glass. Our cars should have been built with infrared reflective windshield glass.
 
I live in Australia where summer temps become extreme, my two Mazda's don't have this particular part number sensor, however I note in many occasions owners 'adjust' settings even when on Auto AC and allow Fresh air intake where it always should be on recirculating when temps are extreme as you are asking a lot of the car/compressor/evaporator to cool down very hot air coming into cabin and the cabin at the same time, rather than cooling ONLY the recirculating air inside Cabin.

Or having 'a' window down 3 inches or more makes AC work harder where it will always underperform.
 
So they have to remove the entire front bumper cover to replace the sensor. Perfect.
You don't have to remove the whole bumper. Just remove the screws and push pins along the top edge of the fascia under the front edge of the hood. It will give you enough forward movement to pull the top of the fascia torwards you to reach down and pull the sensor from its bracket. You can undo the wiring through the grille.
 
Thanks for posting.

My CX9's HVAC is pretty lack luster in the summer. In the winter, my only major complaint is that when it's very cold the engine does not warm itself up enough at idle (annoying during COVID when we had to wait in parking lots a lot) and also that when 'auto' is selected, the front defrost is rarely turned on (even when it's cold, raining, and when I have the rear defrost turned on which leads me to believe that the 'auto' feature's not terribly smart).
 
Thanks for posting.

My CX9's HVAC is pretty lack luster in the summer. In the winter, my only major complaint is that when it's very cold the engine does not warm itself up enough at idle (annoying during COVID when we had to wait in parking lots a lot) and also that when 'auto' is selected, the front defrost is rarely turned on (even when it's cold, raining, and when I have the rear defrost turned on which leads me to believe that the 'auto' feature's not terribly smart).
I have a 2009 Mazda5 with auto climate control, and the logic was better in that car. In the winter it will select defrost and floor vents, and leave it like that. The CX-9 will select the defroster and floor when the engine is warming up, but then switch to floor only.
 
Is this considered an in warranty repair I assume? Meaning tough luck if you are out of warranty.
 
Is this considered an in warranty repair I assume? Meaning tough luck if you are out of warranty.
TSB's are considered specific instructions for a repair. Typically out of pocket for those out of warranty.
 
I have a 2009 Mazda5 with auto climate control, and the logic was better in that car. In the winter it will select defrost and floor vents, and leave it like that. The CX-9 will select the defroster and floor when the engine is warming up, but then switch to floor only.
In my CX5, it does the same thing, however there is still some air going to the defrost vents and this is further confirmed by the owner's manual confirming. When the floor setting is selected, air actually comes out of the floor AND the defrost vents. I suspect it's the same with the CX-9 but that's something you may want to check.

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