Fun little quirk?

[okgo]

My 2006.5 Jetta TDI (1.9L BRM) does something strange with the AC. The car is a 5-spd manual, and I notice something odd when driving the car in reverse. Shifting into reverse does nothing, but when DRIVING in reverse over even just a few MPH, the AC begins to blow probably 2x the volume! Stopping or shifting into any drive gear causes AC to blow normally again. This is so confusing, has anyone notice this quirk?

 

[GreenLantern_TDI]

This is a function of the computer. There is a thread where the how-to stop this is discussed. This does wear something out IIRC.

 

[banshee365]

When reversing, the recirc flapper switches to using in-cabin air for the intake which increases duct pressure making it blow harder on the same fan setting. This is done to try to prevent reversing over exhaust fumes and sucking it through the AC making it smell. This is German over-engineering at its best.

 

[325_Guy]

Does the AC blow with twice the volume, or twice the sound? There should be negligible difference in the airflow whether the interior fan is inhaling outside air or recirculating cabin air...the noise becomes a lot louder because the intake of air is just as loud as the expulsion of air at the vents.

Either way, the prior explanations were spot on...the car automatically switches the climate control to recirc when you are driving in reverse. It does the same thing when you activate the windshield wash fluid sprayers, fyi.

 

[tdiatlast]

Blower speed stays the same. Only the sound changes, IIRC.

 

[ro.sniper]

As mentioned it goes to recirculate function when reversing. Another fun fact is that when you spray your windshield it does the same thing. Bot to prevent the smell from entering the cabin.

Cheers,

RS