Not that it matters as it doesn't affect anything, but was just wondering why the heater vents blow air out faster while in reverse?

Edited 12 July, 201510 yr by mathewwaldock

It's automatically doing recirc mode so you don't suck in exhaust gases whilst reversing.

Mine doesn't do it ... 

Noticed this for the first time yesterday. Then it crops up on here.... Sketchy.

On some cars this may happen sometimes, not other times. My 2003 Polo is like this, but I have every possible fault code for the recirc motor when I scan it with VCDS, so I'm not surprised, nor all that bothered. 

Mine doesn't do it ... 

 

Your recirc motor might be kaput then.  What happens when you push the recirc button on the control panel?

I guess a duff reverse-light switch might cause it not to work too. (Assuming  that's what the ECU involved uses to sense that the vehicle is reversing)

I guess a duff reverse-light switch might cause it not to work too. (Assuming  that's what the ECU involved uses to sense that the vehicle is reversing)

 

Yes, and assuming you already knew that your switch was dodgy, you automatically knew why the recirc mode wasn't working :P

Recirc is working, I'm keeping it on always when AC is running. When scanning it, doesn't show any issues regarding this thing. Should this be activated via VCDS or it's a standard, default feature ? I'd check the wiring, but not sure where to start from. My reverse light (only one) is working, I'm also getting a video feed from my backup camera when switching to reverse. It should be ok.

Later edit: when using the front windscreen wipers and I'm switching to reverse, the one from the back is starting to work. 

Edited 13 July, 201510 yr by Alexandru

Yes, and assuming you already knew that your switch was dodgy, you automatically knew why the recirc mode wasn't working :p

Well, yes, if you thought about it. And you knew it was dodgy.

You will also find that if the front wipers are on, either intermittent or continuous, the rear wiper will complete one sweep when reverse gear is selected.

 

SN

Yep, it already does that, but doesn't switch the blower to recirc. Can't tell why. Does it have a wire that I should check ?

Does the light on the recirc button come on when you select reverse? I guess not?

I just tried mine earlier, and the light does come on, so the ECU is registering that it's supposed to do something, and putting that LED on. Might be a clue as to whether yours is programmed to do it or not?

Okay, just a variation on this theme, wife's 52 plate Polo, always switching recirc air when reverse is selected, but it give a cheeky little short burst of recirc air when the car is stopped - from previously moving foward, and has done for years, no fault codes on that motor though.

Edited 13 July, 201510 yr by rum4mo

Does the light on the recirc button come on when you select reverse? I guess not?

I just tried mine earlier, and the light does come on, so the ECU is registering that it's supposed to do something, and putting that LED on. Might be a clue as to whether yours is programmed to do it or not?

 

Just tried mine, light on button doesn't come on with blower on and reversing, so looks like the base models aren't programmed for it. They must not be bothered that poverty spec owners get gassed when reversing

Look on the bright side; your recirc motors will probably last the life of the car, instead of getting overused on what is basically a gimmick, rather than something really useful.

Look on the bright side; your recirc motors will probably last the life of the car, instead of getting overused on what is basically a gimmick, rather than something really useful.

 

Haha, yeah

I think you have an air quality sensor that triggers the recirc when the car is in reverse. It might be not just a coding though,

I think you have an air quality sensor that triggers the recirc when the car is in reverse. It might be not just a coding though,

 

That could explain the way it works on wife's Polo, maybe it only switches like that when I am in the car (gas issues?).

Usefull literature

 

interesting stuff:

 

1. It is not possible to select the recirculated air mode in every position of air distribution. The recirculated air switch is blocked electronically in the “Defrost” position. This avoids the risk of the windscreen misting up if the interior air is moist. When the ignition is switched on, the positioning motor moves back automatically into the “fresh air” position. It is possible to overcome this blocking mechanism by pressing the switch twice. - I'm keeping it always on the windscreen position, even if it's summer and I don't have to defrost it. Maybe this is why it wasn't getting into recirc mode automatically ?!

 

2. As a general rule, the compressor is operated only by means of the “AC OFF/ON” control. It continues running at “OFF”, supplying about 2 % of the refrigerant total volume which flows back over a bypass through the open control valve into the compressor housing and from there flows again into the inlet chamber.

 

3. The outlet temperature downstream of the evaporator can be regulated from +3 to +13˚C. - really interesting, I might do further research about this, I wouldn't mind having it blow a bit colder.

 

4. The compressor is reduced to part load at the request of the engine control unit, for example, in line with the vehicle acceleration. - I noticed that when going downhill engine braking, it's blowing a bit colder than usual. 

 

It doesn't say anything about an automatic recirculation process or any air quality sensors, as the cars with Climatronic have. (maybe the Polo has it).

Edited 14 July, 201510 yr by Alexandru