CX-9 is full of hot air (Literally)

Getting hot air when I don't want it is sporadic -- happens now and again but not all the time.

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Make a video with your thermometers. When you are at the dealer it'll never get hot. As soon as you get home it'll be roasting. Show the video to the service writer, maybe even stop in in advance when it is blowing hot air if that's convenient and set up the work for the future date.

Hanpra, just a guess is that some control component is getting too hot and shutting off your system. A complete air conditioning system diagnostic might be needed.

hanpra said:

Over my last two trips, even when the AC is switched on, it simply stops cooling after the first 20 minutes, for that entire trip (say a 50 KMS trip). An engine switch on/switch off helped the first time but cannot be all the time (say if on a freeway). My CX9 is a week old, the outside temperatures are 42-45 degrees C. Anyone else has experienced this, car has done 600kms, waiting for the 1000km inspection.

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That is not normal. I've checked the manual and the only mention of the climate control system may not operate properly is if temperature is around 0C (32F).

@chacheee did you manage to find a resolution, and gain any further insight?

I have the same issue, a/c off, auto off, front and rear set to 15C, as it's the time of the year where no a/c is required, just cool outside air. I find the rear vents are blowing warm air (front seem fine) after a while. I'm seeing the dealer tomorrow, so will report back.

I also reported the same issue with my 2017. Wondering if they fixed it in 2019 models. Also the center console storage is warm/hot as well. Poor design since I never had this issue my Honda or acura.

chacheee said:

Can anyone out there check your and see if you get similar results?

I expect the air temp from the vents should be closer to ambient but want to see if this is an issue with my car, or others as well.
Thanks in advance!!!

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OP, this is clearly a design problem on the part of Mazda. They got most everything right with the new CX-9 G2 design but they did miss some things that are rather annoying. The Side Air Vents are nearly useless when blowing with AC on and your complaint of "hot air" coming through not matching OAT is definitely another annoyance. The solution was quite simple - so I'm a little befuddled on how Mazda failed to both Source and Route the outside air coming into the cabin more effectively, so that it does not pick up too much heated air from under the hood. The engine compartment of this vehicle runs temperatures higher than any other vehicle I've ever owned. This means, Mazda is not evacuating the air through the hooded area efficiently enough. However, even on the hottest of days, my engine temperatures have only rarely peaked over 200-degrees F and typically run near the 190-degrees F range.

With that giant opening in the front grill (massive), one would easily assume cooler temps under the hood. However, most of that opening in the grill supports the cooling of the radiator and thus the engine coolant. But, given the higher under-hood temps, it makes me wonder just how 'hard' the coolant is working to keep things within range. I have not yet taken an infrared temperature probe to the engine compartment and its various components, but I'd bet dollars to barbecue ribs that the lower side of the engine runs real hot.

Yet, another good reason to go 100% Full Synthetic Oil, if you have not done so already - by the way. This is not an engine that I would personally cheap out on regarding engine oil and I would never allow my engine oil to go more than 7k without being changed.

Yep, she runs hot with less than optimal air handling into the cabin and that's just the way it is I'm afraid.

Is the issue with 2018 and 2019 models as well?

PTguy said:

Was the engine up to temp? Many modern cars do not shut off the hot coolant that circulates through the heater core even when no heat is requested. There are air control dampers (flaps) in the heating & cooling air system that open or close to give heat or air con air or a mixture of the two. If the flaps do not shut tightly, then it's easy to get the hot air when no heat or cooling is switched on. This will be a warranty item. Sometimes when we complain that the AC is weak, really it the AC running fine but the flaps allowing heated air to sneak by.

So...check the air temp from the vents when the engine is cold. And, check the temp parked in the shade when the engine is warm. If the temp rises with the warm engine, you need the flaps adjusted or repaired, or the operating mechanism fixed. This should be a warranty claim. It might require dismantling the dash, a big job.

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So you have a 2016 cx9 and you dont have this issue?. it means it is just something worng with his car only? strange i tried 2 cars until now 2017 having the same issue. letting hot air while the outside temp is around 10 c and the air coming from the vents is very hot like 45 c. while the temp is set to 15 and no ac on and circulation is off.

anas_tair said:

Is the issue with 2018 and 2019 models as well?

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Same with 2018. Not sure about 2019, but I doubt seriously Mazda did any revisions in this regard.

I want to stress that while this is an issue for aircon "off" with outside air "on" and vent "open" conditions, this is not a major flaw in the CX-9 design. The air conditioning system as a whole works just fine and it will keep the interior cabin at a steady lower temperature relative to OAT. And, the Auto function for temperature control in the CX-9 works just fine as well. The problem is in the duct work to the outer vents inside the cabin and the way they went about sourcing ambient air entering the cabin with the vents "open" condition. The CX-9 runs a little warm under the hood and this is obvious causing the issue. However, once you close the air vents and run in the aircon "on" condition, temps will stabilize and the cabin runs very comfortably from that point forward. I've driven through OAT 102-F conditions for hours with aircon "on" and vents "closed" and maintained a spring like 73 in the cabin front and back with fan speeds at about 40%.

She's a little warmblooded under the hood and they source enough true outside air in the flow, that's all.

i think the point was not running with aircon "on" when outside is already cool.

White Pearls said:

Same with 2018. Not sure about 2019, but I doubt seriously Mazda did any revisions in this regard.

I want to stress that while this is an issue for aircon "off" with outside air "on" and vent "open" conditions, this is not a major flaw in the CX-9 design. The air conditioning system as a whole works just fine and it will keep the interior cabin at a steady lower temperature relative to OAT. And, the Auto function for temperature control in the CX-9 works just fine as well. The problem is in the duct work to the outer vents inside the cabin and the way they went about sourcing ambient air entering the cabin with the vents "open" condition. The CX-9 runs a little warm under the hood and this is obvious causing the issue. However, once you close the air vents and run in the aircon "on" condition, temps will stabilize and the cabin runs very comfortably from that point forward. I've driven through OAT 102-F conditions for hours with aircon "on" and vents "closed" and maintained a spring like 73 in the cabin front and back with fan speeds at about 40%.

She's a little warmblooded under the hood and they source enough true outside air in the flow, that's all.

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I use this option in spring and winter instead of keeping the window down incase i wanted fresh air and wish not to use the AC, cause keeping the window down creats a drag so the option is making the ciraulation off and low temp although the ac is off WORKS WITH ALL CARS ANYCAR and it will let the smae outside tempture air in. Mazda cx9 has an issue .

Just an update. I took the car to the dealer, but unfortunately with no fix. The technician mentioned it's probably the exhaust heating the ducting to the rear vents, and that without the a/c on the air will come out at whatever temperature its been heated to. He got back to me later on saying he saw the same problem on another CX-9, but didn't say if he'll investigate the issue further. I think I'll contact Mazda Australia, as it seems like an issue that affects all CX9s. Funny, for me only the rear vents are warm, and not the front ones as some people are reporting. The work around for me is to manually turn off the rear vents when not using the a/c.