Vents, blowers, air flow, and wind noise

[bobbe]

Apologies in advance if this is a stupid question, but my 05 car does something I've not experienced before with the vents and air and what have you.

If the recirculate slider is set to open (i.e. bringing in fresh air), then air comes in through the vents regardless of whether the fans are blowing or not (unless the vents are closed themselves). If I'm doing any decent speed it's quite a bit of air, and it's hot or cold depending on the heating dial.

If the recirculate slider is closed (i.e. not bringing in fresh air) then nothing comes through the vents when the blower is off. But from about 40mph there is quite noticeable wind noise coming from a point that seems to be inside the cabin, roughly around where the unit is behind the glove box. This is quite annoying.

My 02 car doesn't do this, it behaves quite differently. When the blower is off, no air comes through the vents (as far as I can tell) whether the slider is set to recirculate or not. There is no wind noise from inside the cabin like there is with the 05 car.

The 02 is an A/C car whereas the 05 is not. Is that the difference? The 05 is the first car I've owned without A/C, so maybe it's just not something I've come across before. Admittedly it's only the third car I've owned, but the first was a Ford Focus that was 9 years old when I bought it and miraculously still had working aircon and it behaved in the same way as the 02 car.

Is there something on the 05 car that needs attention or that I can do to stop this? Or is this just a difference between an A/C car and a non-A/C car?

[Call the midlife!]

I don't know about differences between A/C non A/C but there's a grommet in the passenger footwell, through to the frunk area. At least there should be, if it's rotten/missing you might get some wind noise through it.
I'm sure there's a drain there for the A/C blower around the there too.

[bobbe]

I don't know about differences between A/C non A/C but there's a grommet in the passenger footwell, through to the frunk area. At least there should be, if it's rotten/missing you might get some wind noise through it.
I'm sure there's a drain there for the A/C blower around the there too.

Interesting, thanks. I'll see if I can find that grommet (or, failing that, a space where a grommet should be).

Out of interest, is yours an A/C car and does it behave like my 02 or like my 05?

[Call the midlife!]

Neither of mine are AC and in all honesty I don't think I've ever driven with the recirc off so can't say as I've noticed, sorry.

[Topdownman]

I dont think I have ever used the recirculating air either but I assume that it is a flap that closes off the intake. As you build up speed then presumably incoming air from the vent will build up pressure on this flap and if it is not fully closed than I imagine there could be some noise.

I wouldnt worry about it personally and if anything, I would think it a good thing to have a warning system that I was still on the recirculating mode as its not something you would want to use for long!

[bobbe]

Neither of mine are AC and in all honesty I don't think I've ever driven with the recirc off so can't say as I've noticed, sorry.

Sorry, I wasn't asking about AC, I was trying to find out what the normal behaviour for these cars is (so I can try to figure out whether there's anything wrong with mine, and if so what it might be).

In your non-AC cars, with recirculation on, do you notice any wind noise like I described when going over roughly 40mph?

[bobbe]

I dont think I have ever used the recirculating air either but I assume that it is a flap that closes off the intake. As you build up speed then presumably incoming air from the vent will build up pressure on this flap and if it is not fully closed than I imagine there could be some noise.

I wouldnt worry about it personally and if anything, I would think it a good thing to have a warning system that I was still on the recirculating mode as its not something you would want to use for long!

Funny to have one person say they've never driven with recirculation off and the very next person saying you wouldn't want to use recirculation for a long time. Different strokes.

Is your car AC or non-AC? And (assuming you're driving with recirculation off) does air come through the vents when the blower is off?

[bobbe]

I'm trying to find out what the expected or usual behaviour of these cars is so that I can figure out whether my car has an issue, as my sample of two MR2s has a variable (A/C) that potentially changes things quite significantly. The noise is not the point of my question, it is (potentially) a symptom of the point of my question.

[Topdownman]

Funny to have one person say they've never driven with recirculation off and the very next person saying you wouldn't want to use recirculation for a long time. Different strokes.

Is your car AC or non-AC? And (assuming you're driving with recirculation off) does air come through the vents when the blower is off?

Both my cars are non a/c. On the re- circ setting, you are not getting any fresh oxygen in the car other than from leaks which is why I think it should only be used briefly.

Have you looked at the owners manual? Pages 148/9 show which vents work on different settings. I dont think the re-circ should change which vents work if you have the fan on, with the fan off then they wont work. The only faults that spring to mind would be a hose not connected to a vent (if the vent worked under any setting then it couldnt be this though) or a fault with the operating cable or switch on the hvac control.

Might be worth running through all the settings with the fan on to check the vents are working as per the manual?

[Call the midlife!]

Sorry, I meant one thing and pretty much said another, I can't even remember a time when I've driven with the recirc ON for any longer than to demist the windows and that's usually low speed so can't really attest to any difference in airflow.
And my most driven car is that noisy I'd probably not hear anything other than engine or wind rush over the roof.

[bobbe]

Both my cars are non a/c. On the re- circ setting, you are not getting any fresh oxygen in the car other than from leaks which is why I think it should only be used briefly.

Have you looked at the owners manual? Pages 148/9 show which vents work on different settings. I dont think the re-circ should change which vents work if you have the fan on, with the fan off then they wont work. The only faults that spring to mind would be a hose not connected to a vent (if the vent worked under any setting then it couldnt be this though) or a fault with the operating cable or switch on the hvac control.

Might be worth running through all the settings with the fan on to check the vents are working as per the manual?

When recirculation is off, do you - on your cars - get air coming through the vents when the blower is off?

[bobbe]

Sorry, I meant one thing and pretty much said another, I can't even remember a time when I've driven with the recirc ON for any longer than to demist the windows and that's usually low speed so can't really attest to any difference in airflow.
And my most driven car is that noisy I'd probably not hear anything other than engine or wind rush over the roof.

When recirculation is off, do you - on your cars - get air coming through the vents when the blower is off?

[Call the midlife!]

When recirculation is off, do you - on your cars - get air coming through the vents when the blower is off?

Sorry, as I say, I can't confidently answer that as I've never really taken much notice.
If I'm top down the blower will be on, same as if I'm top up, very rarely turn it off.

[bobbe]

Sorry, as I say, I can't confidently answer that as I've never really taken much notice.
If I'm top down the blower will be on, same as if I'm top up, very rarely turn it off.

Okay, thanks.

That's also an open question to anyone else with a non-AC car: When recirculation is off, do you - on your car - get air coming through the vents when the blower is off?

[MikeBoo]

Okay, thanks.

That's also an open question to anyone else with a non-AC car: When recirculation is off, do you - on your car - get air coming through the vents when the blower is off?

Yes, isn't that's what's supposed to happen.
Every car I've owned has been the same. How much air is dependent on the car. Like you've observed the MR2 appears to have a clear duct run to the vent so can be quite forceful at speed, whereas with other cars there is very little flow with the fan off.

[Topdownman]

When recirculation is off, do you - on your cars - get air coming through the vents when the blower is off?

As said above, on recirc., the vents still work but they are just drawing air from the car and blowing that around to whichever vents you have working. The flow will be less than on non recirc though because there is no air being forced in as well.

[bobbe]

Yes, isn't that's what's supposed to happen.
Every car I've owned has been the same. How much air is dependent on the car. Like you've observed the MR2 appears to have a clear duct run to the vent so can be quite forceful at speed, whereas with other cars there is very little flow with the fan off.

Thanks.

Like I say in the OP - this doesn't happen in my 02 MR2 with A/C. In that car, air only comes through the vents when the blower is running (and this was the same with the Focus with A/C that I owned in the past)

My 05 (non-A/C) MR2 does behave as you describe.

[bobbe]

As said above, on recirc., the vents still work but they are just drawing air from the car and blowing that around to whichever vents you have working. The flow will be less than on non recirc though because there is no air being forced in as well.

I appreciate your trying to help, thank you, but unless I'm reading you wrong in this and your previous post you seem to be talking about something other than what I'm asking about. You seem to be talking about what happens when recirculation is on and the blower is on. I am asking what happens when recirculation is off and the blower is off.

An yes or no answer to this question would be really helpful: When recirculation is off, do you - on your cars - get air coming through the vents when the blower is off?

[Topdownman]

Perhaps I misunderstood, when not on re-circ ie with the air coming from outside, air does come through the side vents and windscreen ones but not as strongly as it does when using the centre vents. Not sure if this is just because I feel the flow from the centre vents as they are nearer and blowing on me more.

(Not quite a yes or no answer but more on the yes side!).

[bobbe]

Perhaps I misunderstood, when not on re-circ ie with the air coming from outside, air does come through the side vents and windscreen ones but not as strongly as it does when using the centre vents. Not sure if this is just because I feel the flow from the centre vents as they are nearer and blowing on me more.

(Not quite a yes or no answer but more on the yes side!).

Okay, thank you!

[Ardent]

@bobbe
Mine is an FL car that is fitted with AC.
With slider set to flow through/outside air.
Fan off.
Yes air flows through vents.

[bobbe]

@bobbe
Mine is an FL car that is fitted with AC.
With slider set to flow through/outside air.
Fan off.
Yes air flows through vents.

Oh, interesting! This does raise the possibility (which I admit I had not considered) that it might in fact be the 02 car that has something up with it, since it doesn't do this

[MikeBoo]

Oh, interesting! This does raise the possibility (which I admit I had not considered) that it might in fact be the 02 car that has something up with it, since it doesn't do this

I answered your post #14 as requested being a non-AC MR2 owner.

It certainly does seem like there is a problem, especially as 2 other current non MR2 cars that have aircon also operate as I described as well as all of those I have previously owned with or without aircon.
At a guess it seems as though a vent pipe may have come loose, dislodged or something is blocking the inlet or pipe to the vents.