Vents blow abnormally warm air

[daytona rs7]

I'm hoping to get people's experiences regarding the vent temperature of their car, specifically anyone with the 4.0t.

My situation is that with with the AC off/fan on, my car seems to blow abnormally warm air.
Maybe this is how everyone's cars are?

Everything seems to work correctly. Temperature adjustments and fan speed do work. But it just seems that the scaling for what temp I want is "off".

65 degree setting will blow uncomfortably warm air. If I turn up the temp, it blows hotter air. If I turn the temp down and put the Ac on, it blows ice cold. It just seems as though a mid 60s temp setting is trying to heat the cabin to 80+ degrees. This is not a warm weather issue, as it happens in winter too, just less severe.

I'm just not sure why a "comfortable" temp of 65 degrees blows abnormally warm air.

For comparison, my Mercedes or Land rover will blow appropriate temps with the ac off/fan on.

Maybe this is because the 4.0t runs very warm and so air temps will always be warmer than most?

Anyway, what's everyone's experiences with this?

[Rob4.2]

might be the A/C Pressure switch

https://www.europaparts.com/air-cond...h0959126b.html

or

https://www.europaparts.com/air-cond...9126b-oea.html


before someone tells you it's a compressor issue try that first

[daytona rs7]

Thanks, but this is not AC related. The problem is only when the AC is off.

I think it's more related to the heater core inability to cool the hot engine bay air.

I realize that statement sounds weird, but it's the best way I can describe it. It's as if the heater core is constantly creating warm air, even when the vent temp is set low.

Maybe my solution is simple as always have ac on?
But that seems like a fix to a problem I shouldn't have.

[STalon92]

I noticed this same thing on my S6 yesterday. Feels like the heat is on.


Sent from my iPhone using Audizine

[Caker]

On both of the S7's I've had I noticed the opposite issue, I want warmer air and it blows cold even with the A/C off and the temp cranked up fairly high. I eventually figured out that when I have a window open, it acts weird and blows cold air but when the windows are closed it acts normal. Perhaps there is a temperature sensor inside the car that isn't reading cabin temp correctly and it being affected by the wind coming in through the window. Are your windows open when you experience the issue?

[daytona rs7]

On both of the S7's I've had I noticed the opposite issue, I want warmer air and it blows cold even with the A/C off and the temp cranked up fairly high. I eventually figured out that when I have a window open, it acts weird and blows cold air but when the windows are closed it acts normal. Perhaps there is a temperature sensor inside the car that isn't reading cabin temp correctly and it being affected by the wind coming in through the window. Are your windows open when you experience the issue?

I have not noticed any difference with the windows open/closed.
But I will typically open my windows since the air coming out of the vents is significantly warmer than the outside air.

The inside air temp sensor is an interesting theory, but I would think that I'd notice a temp issue when the AC is on also....but i dont.

[gk1]

Yeah I sort of see what you are saying, certainly 65 with A/C on is not the same as 65 with A/C off. You'd think they should be but they are not.
70-72 with A/C on seems to be about right. I can't say it is "uncomfortably" warm as you mention with A/C off, but it does usually drive the fan harder to try to maintain the set temp without A/C on and if it is above 65 outside it really cannot do it.
The only suggestions I have are:
Cycle through all the vent distribution adjustments I've heard of some getting stuck and then perhaps it could be as you said it is passing through the heater core when it should not be.
Check footwell temperature setting...I know it sounds dumb as that "should" only effect the footwell, but again stuck vent distribution damper somewhere may affect things differently.
Check coolant mix. If it is not 50% or max 55% per spec it could potential affect things like heating and cooling, both interior and engine.
Audi tool to check coolant T10007A or B now but you can find cheaper version on Amazon
https://erwin.seat.com/workshop/en/f...0007b_1817.htm
They all seem to be the same made by ATC.
https://www.amazon.com/s?k=coolant+r...f=nb_sb_noss_2

Also for reference these should be the cabin HVAC sensors. (Excluding outside air temp & A/C pressure/temp)
(Just a quick parts lookup, don't have em all and as always check the p/n yourself if you plan to replace any.)
G238 air quality with humidity sensor. In the fresh air intake under the windshield cowl.
G150 Left vent sensor. Up under the driver's dash panel. 3D0907543A
G151 Right vent sensor. Behind the glove box. 3D0907543A
G261 Left footwell vent. Under driver's side panel
G262 Right footwell vent. Behind glove box.
G637/G638 Rear footwell vent. Under the front seats. 4B0820539
G635/G636 Rear upper body vent. Under the center console (Rear center 3D0907543A?)
G623 Evaporator vent sensor. Behind passenger's side footwell vent behind glove box. (4H0907543?)
G107 Sunlight photo sensor. Center dash near windshield.
AFAIK the sensor in the HVAC controls is not a separate part and is only a part of that whole panel.
But as you said any one of them if truly faulty should generate a DTC. However when my outside temp sensor failed on my SQ5 it did not set a DTC since it is just a simple thermistor. I'm sure you could find them all in VCDS and just check to see the temperatures register what you expect and one is not wildly off maybe.

[daytona rs7]

Thanks for the suggestions gk1.

i understand 65 degrees vent setting will not create equally temperature air with with the AC on or off, but there is a significant delta between the way the air feels.
when AC is off and temp sent to 65, i feel as if its pumping out air that feels as though its 80+ degrees.
The air coming out of the vents is always hotter than the ambient temp outside.


Interesting you say to cycle the vent selection though. I think the car has been set to AUTO for nearly its entire life. Maybe a change to the air distribution will give it the "reset" it needs to divert air correctly.

FYI, this condition has been like this since i bought the car new, 3 years ago. only getting around to complaining about it now because Im tired of hearing the wife complain about it.

Ill also try to get some actual temp measurements tonight in order to compare ambient VS vent temp, both with the car at cold start and warmed up.
After i get some solid numbers and prove im not just overly temperature sensitive, ill dig into VCDS and check temp readings.

[Horia]

Hi! How you solve the problem? since few weeks my car also started to do same hot air problem with Ac off, this was not there until now and i have the car since 2018…. Can you please replay? Thank you

[Horia]

I'm hoping to get people's experiences regarding the vent temperature of their car, specifically anyone with the 4.0t.

My situation is that with with the AC off/fan on, my car seems to blow abnormally warm air.
Maybe this is how everyone's cars are?

Everything seems to work correctly. Temperature adjustments and fan speed do work. But it just seems that the scaling for what temp I want is "off".

65 degree setting will blow uncomfortably warm air. If I turn up the temp, it blows hotter air. If I turn the temp down and put the Ac on, it blows ice cold. It just seems as though a mid 60s temp setting is trying to heat the cabin to 80+ degrees. This is not a warm weather issue, as it happens in winter too, just less severe.

I'm just not sure why a "comfortable" temp of 65 degrees blows abnormally warm air.

For comparison, my Mercedes or Land rover will blow appropriate temps with the ac off/fan on.

Maybe this is because the 4.0t runs very warm and so air temps will always be warmer than most?

Anyway, what's everyone's experiences with this?

Hi

[Spitfire007]

I think these cars are made to run in auto with AC on all the time. It seems to work best for me, but I do occasionally go full manual.

One trick to cool the air is to use the AC when manual temps are selected to cool the air a second, and then just turn the AC off, leaving the fan, vent selection and temps where you want them


Sent from my iPhone using Audizine

[Horia]

I did not had this problem until now. Since 2 weeks started to blow boiler air inside only when Ac off. I have the car since 2017 so i know how it works… when outside is 17C on auto with ac off it s like 28 inside, i sett it on all fan steps and temps, auto manul all, no vcds error. I ll recheck for errors next day….

[Botbasher]

I know my B8 had a AC flap "calibration" in the MMI. Think it was under "Car" then "AC" then "Calibration" IIRC... it's been a while.

I don't have my car handy to see if it's still an active option, but worth checking. Maybe there is an Adaptation for it now?

If the flaps are not closing all the way they could be letting excessive heat through!

Cheers,

KS

[Horia]

I have Rs7 2016, don t know if it same like b8 on ac and climate control…