CX-9 is full of hot air (Literally)

chacheee

Member
:
CX-9 GT 2017
Hi all,
Has anyone else noticed that their CX-9 is always blowing hot air? I have a 2017, and driving home today I noticed how warm the cabin was. The temp outside was about 25c, so I had the AC off. The air blowing from both the front and rear vents was noticeably warm. (Much hotter in the back)

When I got home I checked the temps using a meat thermometer. See the pics below. With the outside temp reading 27c, and the temp set to 15c, the front vents was blowing 35c and the rear vents were 40c. That’s about 105F !!)This was sitting in the shade, with the fan running at 2/3 of max.

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!!!

406705eb336ac0a7449545c86a7b28e3.jpg
8270e40bcbcf75dba9d54468c857c015.jpg
 
Probably due to not having dials for closing any of the vents.

Try and change the setting (yes when the climate control is off) to recirculate by pressing that button and see if that stops the air flow.
 
Hi all,
Has anyone else noticed that their CX-9 is always blowing hot air? I have a 2017, and driving home today I noticed how warm the cabin was. The temp outside was about 25c, so I had the AC off. The air blowing from both the front and rear vents was noticeably warm. (Much hotter in the back)

When I got home I checked the temps using a meat thermometer. See the pics below. With the outside temp reading 27c, and the temp set to 15c, the front vents was blowing 35c and the rear vents were 40c. That’s about 105F !!)This was sitting in the shade, with the fan running at 2/3 of max.

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!!!

406705eb336ac0a7449545c86a7b28e3.jpg
8270e40bcbcf75dba9d54468c857c015.jpg

In those pictures the A/C isn’t actually on. Just the fan. So it’s blowing air from the outside. Press the AC button - the orange light will come on.
 
In those pictures the A/C isn’t actually on. Just the fan. So it’s blowing air from the outside. Press the AC button - the orange light will come on.

Nice pick up. Totally missed the fan(s) being on!
 
Nice pick up. Totally missed the fan(s) being on!

That’s absolutely correct. I understand that the air won’t be cooled, but it also should not be heated. With an outside air temp of 25C and the HVAC set to 15C, I expect that the blower would simply draw air in from the outside and 25C air would blow into the cabin.

The issue i have is that the air coming is is about 10C-15C (18F-27F) above the outside air temp, when the air shouldn’t be heated at all.


The AC works fine. The concern that I have is that I shouldn’t have to run the AC, to simply get outside air into the cabin, without being heated.
 
That’s absolutely correct. I understand that the air won’t be cooled, but it also should not be heated. With an outside air temp of 25C and the HVAC set to 15C, I expect that the blower would simply draw air in from the outside and 25C air would blow into the cabin.

The issue i have is that the air coming is is about 10C-15C (18F-27F) above the outside air temp, when the air shouldn’t be heated at all.


The AC works fine. The concern that I have is that I shouldn’t have to run the AC, to simply get outside air into the cabin, without being heated.

It might say 25 outside but the actual air around the car is warmer than that based on where the HVAC is drawing this air from. Therefore the air is warmer coming inside of the vehicle via the fan (air con off)
 
Thats absolutely correct. I understand that the air wont be cooled, but it also should not be heated. With an outside air temp of 25C and the HVAC set to 15C, I expect that the blower would simply draw air in from the outside and 25C air would blow into the cabin.

The issue i have is that the air coming is is about 10C-15C (18F-27F) above the outside air temp, when the air shouldnt be heated at all.


The AC works fine. The concern that I have is that I shouldnt have to run the AC, to simply get outside air into the cabin, without being heated.

What was the temp at the air intake for the HVAC under the hood?

If the car is on, or has been on, the underhood is going to be warm.
 
Turning off the fan(s) and next to no warm air should enter the cabin...
 
What was the temp at the air intake for the HVAC under the hood?

If the car is on, or has been on, the underhood is going to be warm.

Of course the car was on. [emoji6]

I’ve owned lots of cars, and the is the first one where on a nice warmish day that I’ve had to put the ac on to stay comfortable. Maybe this is normal....but when you guys are out and about in the next couple days, do you mind running for a bit with the same settings I did (no AC and no heat) and see if you get hot air from the vents....especially the rear?

I just want to see if this is typical before I take it in for my next service.

Thanks!!
 
Most auto HVAC intake vents are at the base of the windshield where the windshield wipers sit. In looking at your photos, your speedometer appears to show 0kph, so you're completely still (probably doing this in your driveway). Consequently, you're not getting "fresh" air moving across the car towards the intake vents. Rather, you're getting air that has been heated by the sun, air that has been heated by the windshield (which has been heated by the sun), and air that has been heated by the hood (which has also been heated by the sun as well as by the running engine). This is my guess as to why the temperature of the air coming out of your HVAC vents is so much hotter than the outside ambient temperature. (And, of course, because you don't have the A/C compressor actually activated.) My guess is that if you were moving, the air, while still warmer than the outside ambient temperature, would not be as warm as the readings you're getting just sitting in your driveway.

Just my $0.02....
 
Most auto HVAC intake vents are at the base of the windshield where the windshield wipers sit. In looking at your photos, your speedometer appears to show 0kph, so you're completely still (probably doing this in your driveway). Consequently, you're not getting "fresh" air moving across the car towards the intake vents. Rather, you're getting air that has been heated by the sun, air that has been heated by the windshield (which has been heated by the sun), and air that has been heated by the hood (which has also been heated by the sun as well as by the running engine). This is my guess as to why the temperature of the air coming out of your HVAC vents is so much hotter than the outside ambient temperature. (And, of course, because you don't have the A/C compressor actually activated.) My guess is that if you were moving, the air, while still warmer than the outside ambient temperature, would not be as warm as the readings you're getting just sitting in your driveway.

Just my $0.02....

This is probably a big part of it. Can the OP repeat the test while driving at a low speed, then a higher speed? Sometimes the HVAC can pull underhood air into the intakes as well. It's quite warm under the hood, but moving at even a low speed will drop the temperature to near ambient immediately.

The only other possibility I can think of is that the valve that controls the heater is not completely closing, so you are getting hot engine coolant circulating through the heater core, even with the heater off.
 
This is probably a big part of it. Can the OP repeat the test while driving at a low speed, then a higher speed? Sometimes the HVAC can pull underhood air into the intakes as well. It's quite warm under the hood, but moving at even a low speed will drop the temperature to near ambient immediately.

The only other possibility I can think of is that the valve that controls the heater is not completely closing, so you are getting hot engine coolant circulating through the heater core, even with the heater off.

If the vents had dials allowing closure, this would solve that later issue.
 
Hi all,
Has anyone else noticed that their CX-9 is always blowing hot air? I have a 2017, and driving home today I noticed how warm the cabin was. The temp outside was about 25c, so I had the AC off. The air blowing from both the front and rear vents was noticeably warm. (Much hotter in the back)

When I got home I checked the temps using a meat thermometer. See the pics below. With the outside temp reading 27c, and the temp set to 15c, the front vents was blowing 35c and the rear vents were 40c. Thats about 105F !!)This was sitting in the shade, with the fan running at 2/3 of max.

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!!!

406705eb336ac0a7449545c86a7b28e3.jpg
8270e40bcbcf75dba9d54468c857c015.jpg

Doesn't the air flow thru the engine compartment? I'm not sure that non A/C air coming thru the vents is the ambient temp.
 
I am not sure if it is the case in this instance, but I have seen that since the advent of cabin air filters, some manufacturers use the HVAC plenums to help cool heat sinks from the cars electrical system components.

The air to the rear vents will also be warmed up by the heat-soak into the floorboard by the exhaust system.
 
chacheee: I experienced exactly the same thing the other day. A warm spring day, maybe 18 or 19 degrees, roof open and no need for AC, HVAC temp set to 15 -- minimum -- and hot air blowing through the vents. It was made doubly bad by the fact that you can't close the center vents. After maybe ten minutes of this I turned on the AC and then turned it off about ten minutes later, and from that point on cool air blew through the vents, even long after the effects of the AC had gone. It was as if the system had been stuck on 'heat' and turning on the AC for a while somehow triggered turning off the heat.

Weird.
 
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.
 
I must be one of the few people who don't have the fan running while AC is off and therefore don't experience this....
 
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.

I think you may be correct here. Getting hot air when I don't want it is sporadic -- happens now and again but not all the time. It could well be a sticky vent that gets closed properly when I turn the AC on. I'll notify the dealer when the car goes in for its next service (soon).
 
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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