Rear air conditioning better than the front

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Mazda cx-9 2008
Hello. the forum is always there to help. I'm counting on you. Air conditioning system after the service. gas is. Tightness tests are good. I have a strange situation. Whether in the machine or I give manual control of the air conditioning temperature in the back for the 2nd row of seats, I have cool air. The climate works fine. It is worse at the front. The passenger is worse than the back. It is poorly cooling the driver's area. What's the problem?
 
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Mazda CX-9 Grand Touring 2016
The air flow is controlled by flaps in the ducts. If one or more are not moving correctly then you can get the problem you describe. With the system set on manual run the fan on high. Set the heat on high. Move the controls to change the direction of the air flow...feet, face, windshield, etc. Does the air flow correspond to the controls? Now set the temperature on the coolest, give it a few minutes to cool down, and do the same with the controls. Does the air flow change as you change the controls? If not it may need a repair to the flaps or their actuators.
 
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16 CX-5 Tour'ngAWD
Hello. the forum is always there to help. The climate works fine. It is worse at the front. The passenger is worse than the back. It is poorly cooling the driver's area. What's the problem?

as mentioned above, it could be the blend door (controls direction of air selected on dial) as they are called may not be closing or opening fully.

Here is another kicker, on each blend door (if more than one), there are usually holes. The blend door itself is not a solid piece (of plastic). The holes in the blend door allow the door to move when the fan is on high; otherwise, the motor would have to fight the full force of the air traveling through the duct/blend chamber, thus causing more stress on all parts.

Also, the blend door will have foam or some other semi-porous material covering the holes to limit the amount of air that "leaks" past the door and directs 90%+ of the air to where you want it to go.

It is possible, that maybe the material that normally covers the holes on the blend door(s) has failed or is compromised and is allowing more cold/hot air to the back vents.

It is also possible that the main back vent duct is nearer the blend door and more air naturally goes to the back before it goes to the front. I do not have a schematic and I've never seen the Mazda blend chamber, so I cannot be for certain what is actually going on.

In the end, it could just be a design snafue and how the main front duct and main rear duct are in relation to the blend door and the rear main duct "wins" getting the coldest or hottest air first.

good luck in finding a solution.
 
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2018 CX-9 GT
Does the cx-9 have a separate core at the back for the second row?

If it does then there could be an issue with the front core that doesn’t affect the rear one. (Clogged line maybe? )
 
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Mazda cx-9 2008
Does the cx-9 have a separate core at the back for the second row?

If it does then there could be an issue with the front core that doesn’t affect the rear one. (Clogged line maybe? )
It seems to me that Mazda has one evaporator under the dashboard.
 
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Mazda cx-9 2008
Thank you. I have a preview. I wish I could download it in pdf.

A colleague said to check the temperature sensor under the steering wheel. It might be dirty. Hence the poor cooling of the driver's seat.
 

Jomoryja

CX9 '07 GT AWD & CX5 '17 Nakama Intense
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CX9 07 & CX5 17
I own a Mazda CX-9 from 2007. I had the problem that the driver side in the front was not cooling. Passenger side in the front was ok. Rear was ok also.
The airco system was checked and contained only half of the refriggerant.
After check for leaks and refill everything is operating again in a good way.

See also :

Warm air blowing from the Drivers side, or Passengers side vents.
 
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Mazda cx-9 2008
How can I check the flap actuator? there are several of them. I assume it's the one near the radio. The temperature sensor under the steering wheel was very dirty. I guess it's not a problem in the sensor anyway.
 
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Mazda cx-9 2008
Hello. The air conditioning is packed and tight. When I change the temperature range from 15 to the maximum temperature, the heater motors are working. They seem to be working. Temperature set to minimum and the rear grille shows 9st on the thermometer after 10 minutes of driving. Passenger airflow 16st and driver airflow 21st. No cold 1 zone. The passenger seat is a bit cold. The rear is working fine.
 
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2018 CX-9 GT
You could try the verification steps in NO.11 DUAL A/C CONTROL DOES NOT OPERATE in the HVAC troubleshooting section of the workshop manual. It is not exactly your symptoms , but I think it would check most of the possible cause for air mix issues.
 
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2018 CX-9 GT
Also, the workshop manual 2008 HVAC Basic System - Mazda CX-9 identifies a front and a rear evaporator. (Item 1 and 8 on the parts list diagram).

for that reason, I think that the fact you have cold air in the rear does not mean necessarily mean you don’t have a problem with your front AC unit.

DD3CBE1F-7B93-49B3-BBD9-C557A1FF3F99.png
 
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Mazda cx-9 2008
You are right. These are two separate systems. I cleaned the cabin sensor. It didn't do anything. I touched the actuators, listened to how they work. Left and right acurators the same. I don't think these are actuators. The front evaporator sensor may be defective? Can he show such symptoms? Unless there is a break in the sewers and the driver is not cold? Can the Mazda service computer diagnose the operation of the air conditioning system? Maybe I should disassemble the cockpit and look for a dirty evaporator core? Thank you for your help.
 
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2018 CX-9 GT
I honestly don’t know much more. In the HVAC diagnosis section, there is a diagnosis procedure for the AC not cooling symptoms, but i don’t have enough knowledge to say if it would help. And i also think some of the steps need specialised tools (check the refrigerant pressure, etc). But have a look it might help
 
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Mazda cx-9 2008
I checked the actuator from the driver. Good gears, by turning the knob, the actuator moves the damper. I think it is operational. I wonder if it's not the fault of the actuator under the dashboard, more for the radio. A colleague told me that it may be a defect in the expansion valve. Cx9 probably has 1 valve. Could he be a problem? Are there maybe 2 expansion valves?
 
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17 CX-9 GT FWD
If there are two evaporators, there will be two expansion valves. The suction tube (large)
should be cold coming out of each evaporator.
 

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