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Discussion Starter · #1 ·
I am trying to figure out if there is a malfunction with the HVAC system in our ascent. I have noticed that driving with the HVAC off, on a cold 50 degree day, that heat builds up in the vents to the point where it is too hot and bothersome and I have to turn the A/C on to clear it. I don't recall this ever being an issue with our forester if the system was disengaged. Do I need to set it to recirculate or set a certain temp before turning it off so heat doesn't come through the vents? Are other people experiencing this? Thanks.
 

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I am trying to figure out if there is a malfunction with the HVAC system in our ascent. I have noticed that driving with the HVAC off, on a cold 50 degree day, that heat builds up in the vents to the point where it is too hot and bothersome and I have to turn the A/C on to clear it. I don't recall this ever being an issue with our forester if the system was disengaged. Do I need to set it to recirculate or set a certain temp before turning it off so heat doesn't come through the vents? Are other people experiencing this? Thanks.
I’m dealing with it too. Drove this weekend to DC from chicago and had to use the air both ways the entire time because the heat when the vents were off was very warm. Recirculate caused moisture build up so that didn’t work.
 

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It was reported here before. I have the same issue. The only workaround I found is to enable ac or recirc air.

I am very disappointed by this design flow on $45k touring trim.

This is my 3rd Subaru. None of the Subarus or any other cars I have Ever owned or rented had such issue.
 

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This was previously reported and I too, run into the same problem. The cabin feels much warmer due to the heat that comes through from the vents, even with the system off. It's annoying, actually. I always tend to have to use the AC (which I hate as it makes the engine runs much louder than normal) just to cool down.

This is in my list of issues for the dealership when I take the car in for first maintenance.
 

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Discussion Starter · #6 ·
Thanks for the responses. I'll look for that other thread. There is another piece to this issue and that is the air quality coming through the vents when hvac is off. I have a sense that there is some mixture of engine smell (burnt oil+gas) that is very faint but noticeable coming through or when vents are first turned on. I wonder if there is an air quality test that the dealer can do. About 2 months ago I had a problem with the A/C quitting (an electrical harness came detached and forced open all of the internal vents as its default, which brought in engine fumes/odor to the cabin) and I am thinking the smells might be a residual of that earlier problem, but can't be sure. It's very subtle (I have a strong sense of smell I am told by my wife) and I am sure the dealer will think I'm imagining things if I try to point it out. But the last thing you want is contaminated air coming into a small sealed cabin space.
 

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This was previously reported and I too, run into the same problem. The cabin feels much warmer due to the heat that comes through from the vents, even with the system off. It's annoying, actually. I always tend to have to use the AC (which I hate as it makes the engine runs much louder than normal) just to cool down.

This is in my list of issues for the dealership when I take the car in for first maintenance.
Sorry for the dumb question, but I'm still researching this car. Does setting the climate control to a specific (lower) temperature cause the A/C to come on, or is that something you have to do manually?
 

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I am trying to figure out if there is a malfunction with the HVAC system in our ascent. I have noticed that driving with the HVAC off, on a cold 50 degree day, that heat builds up in the vents to the point where it is too hot and bothersome and I have to turn the A/C on to clear it. I don't recall this ever being an issue with our forester if the system was disengaged. Do I need to set it to recirculate or set a certain temp before turning it off so heat doesn't come through the vents? Are other people experiencing this? Thanks.
I have the same issue. As soon as I am on the highway and that the engine is hot, heat is coming through from all upper vents as if the system was ON. It's really hot too!

For a couple of times now, I put system ON on AUTO for a minute or so, and turning it OFF again, seems to stop the heat coming through.

I am seeing my dealer in a couple of weeks to investigate this.

Regards,
 

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I read earlier that even if the fan is off, the heater is still trying to heat the air to the temp set on your climate control. So if you turn your temp all the way to low, then turn the fan off, no hot air comes out.

I too had hot air coming out as I set my temp to 78 here in AZ for the A/C and once the temp finally dropped in November, it started blowing hot air at me because the temp outside was 70 and it was trying to heat it to 78! Turned it down to LO and turned the fan off. FIXED!

Now I still think that's an error in the climate control programming. If the fan is off, the system shouldn't do ANYTHING :D
 

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I read earlier that even if the fan is off, the heater is still trying to heat the air to the temp set on your climate control. So if you turn your temp all the way to low, then turn the fan off, no hot air comes out.

I too had hot air coming out as I set my temp to 78 here in AZ for the A/C and once the temp finally dropped in November, it started blowing hot air at me because the temp outside was 70 and it was trying to heat it to 78! Turned it down to LO and turned the fan off. FIXED!

Now I still think that's an error in the climate control programming. If the fan is off, the system shouldn't do ANYTHING :D
This is true, discovered the same issue all the back to my 2011 legacy. When the system is off it continues to control temperature based on the set point of the unit when it was turned off. Seems to me it would be an easy software update to disable or set to Lo when the unit is off but I guess in 8 years Subaru still hasn't figured that out.
 

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My wife noticed the same after we took our 3-day old Ascent on a 30 min drive on the highway. I wouldn't describe it as heated air coming out of the vents, but more of a odor that happens to be coming from somewhere within the hvac that smells almost indistinguishable from second hand cigarette smoke and we actually had to open our windows to vent it was so strong. By the time we finished our drive, the smell lingered in our clothes and I felt as if I had just stepped out of a smoker's car, and neither my wife or I are smokers.

My guess is that it has something to do with the way the air intake to cool the turbo charger is somehow inadvertently heating portions of the hvac causing the odor we describe. Anyone have any other guesses?
 

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Now I still think that's an error in the climate control programming. If the fan is off, the system shouldn't do ANYTHING :D
On all cars I have drove (including 2 other Subies I owned), unless air on the recirc, driving rams air through. not a lot, but sufficient for fresh air in the car

so even though fan is off, air would still go through.
 

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On all cars I have drove (including 2 other Subies I owned), unless air on the recirc, driving rams air through. not a lot, but sufficient for fresh air in the car

so even though fan is off, air would still go through.
Yep.

Folks, when you set a warmer than ambient temperature, the heat exchanger valve adjusts to let hot coolant flow. With the vents open, it means some forced air comes in, and then enters the cabin. Since it's a lower air flow than the fan creates, the air is warmer than you may usually expect.

Fan on or off, turn the temperature to what you want, or as suggested earlier, to "LO" to do nothing and close the heat exchange valve.

There's literally a couple radiators (heat exchangers) IN your car. If the valve is open, the engine coolant flows through them. If it's closed because the system is set to "LO", then that radiator isn't getting heated up.

Here, you can see one of the radiators. The valves are in the engine compartment, IIRC.

 

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Thanks for the responses. I'll look for that other thread. There is another piece to this issue and that is the air quality coming through the vents when hvac is off. I have a sense that there is some mixture of engine smell (burnt oil+gas) that is very faint but noticeable coming through or when vents are first turned on. I wonder if there is an air quality test that the dealer can do. About 2 months ago I had a problem with the A/C quitting (an electrical harness came detached and forced open all of the internal vents as its default, which brought in engine fumes/odor to the cabin) and I am thinking the smells might be a residual of that earlier problem, but can't be sure. It's very subtle (I have a strong sense of smell I am told by my wife) and I am sure the dealer will think I'm imagining things if I try to point it out. But the last thing you want is contaminated air coming into a small sealed cabin space.
Have been reading your post and I must say that I am experiencing exactly the same issues with my 2011 Forester bought as used car last May.

Poor quality hot air comes through the vents when HVAC is off. My wife blames my strong sense of smell and local dealer believes I am imagining things!

I wonder if after three years you have managed to find a solution to this terrible situation.

Concerning the hot air I have read some posts that suggest to turn HVAC to Lo before turn it in off and was wondering if this has worked in your case.

Concerning the poor quality of the air I haven't seen and suggestion in the blog.

Thank you in advance for your support!
 

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Sometime this happens to me as well so I turn HVAC on and lower temperature and then turn off HVAC. This is not the best design...
Thank you for immediate response and relevant confirmation. It seems that this is the only solution to to this weird issue.

Concerning the poor quality of the air coming in at the same time, I just read in other forums, apart from usual suggestions (CV boots, valves cover gaskets, etc), that it would be good to check the PCV valve hose, something that sounds as a rather interesting suggestion.

In any case, will check all the above in practice and will revert.





I
 
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