Drivers aircon/heating slower than passengers?

[Graham Butcher]

Sunday, my son and I went to the Royal International Air Tattoo at Fairford and for a couple of spells in the afternoon it poured with rain and of the problems there is, that there is never enough shelter available for when that happens, so we both got soaked right though to our underwear, despite using umbrellas☹️

 

When we got back to the car, I quickly switched the heating on and after a while my son was complaining about being to hot and he had to turn side down, but myside was sending cooled air. I also had my seat heater on, which did warm me up, so much so that I was comfortable all the way home, some 140 miles. When I got home, I discovered that I was still soaked and was able to wring the water out of my sweatshirt (not so sweaty after all then 🤣).

 

Today I decided to look into the apparent lack of heat and it was true as the photos show (note the yellow meter reads lower temps then the orange one) and I discovered is that the drivers (my side) does indeed take far longer to deliver any heat but the cooled air is about the same as the passengers side, The rear vents are working just fine.

 

Now I'm assuming that there is only 1 heat exchanger for the entire car with 3 ducts coming from the heater box, 1 for each zone with their own flap. I also assume that the same is true for the cooled air?

 

VCDS shows only 1 fault, and that is a bad air quality sensor for the rear vents, so is my problem likely to be a bad servo on the heater flap or a bad control unit, but I would have expected the scan to pick that up, any ideas?

 

[numskull]

You could try a reset, Graham: you do this by holding the auto and face vents switches down together for 30s or so. 

[Danoid]

If the drivers side is better then sod everyone else 😂

 

I doubt it’ll help in the slightest but has your pollen filter been changed? Might be worth removing it the correct way (with cardboard under the filter) then replace.

 

Like numskull said do a reset and let it recalibrate then test again

[Graham Butcher]

2 hours ago, numskull said:

You could try a reset, Graham: you do this by holding the auto and face vents switches down together for 30s or so. 

Should I get some sort of signal when the reset request is accepted? If so what is it?

[SuperbTWM]

Can you do the same test on HI but with the air con off?

 

Maybe the cool blend flap is passing on the drivers side causing it to overcool, obviously turing the AC off will bring the blend air to ambient instead of close to freezing (not 100% sure this is how it works but I thought it was worth suggesting)

Edited 18 July, 2023 by SuperbTWM

[numskull]

12 minutes ago, Graham Butcher said:

Should I get some sort of signal when the reset request is accepted? If so what is it?

Hmmm. Not sure, but there is also the flap relearn procedure too which as follows @ApertureSis this OK to try to solve Graham’s issue?

Turn the ignition on, then off.

Hold the ac and recirculate buttons till the panel starts flashing, then all the flaps will move and relearn their positions 

When the display it stops flashing, cycle the ignition again. 
Graham, wait ‘til AS comes back with the confirmation to go ahead, or not!!

[Graham Butcher]

47 minutes ago, SuperbTWM said:

Can you do the same test on HI but with the air con off?

 

Maybe the cool blend flap is passing on the drivers side causing it to overcool, obviously turing the AC off will bring the blend air to ambient instead of close to freezing (not 100% sure this is how it works but I thought it was worth suggesting)

Yes, I did this test, both on HI and LO and here are the results.

                                     

Front Left  59.6C  &  32.1C

Front Centre Left  48.4C  &  32.5C

Front Centre Right 37.6C  & 31.7C

Front Right  43.3C  & 31.6

Rear  51.5C  & 32.2C

 

There is most certainly a huge difference.

[J.R.]

I believe that you have the full Climatronic system, does it have individual temperature settings for driver & passenger?

 

I am assuming that they were both turned up to the same temperature, there are temperature sensors in the heater pipes, one of yours is probably not giving the true reading so the flaps are doing the wrong job.

 

VCDS will display the readings from all the sensors and the operating angle of the flaps compared to the commanded angle, if the flaps are working properly then the temperature sensor readinsg should be the same for both sides (both set to the same temp) if they are different you just have to work out which is the implausible reading and replace the sensor.

 

I bet you were looking for an excuse to remove your dashboard!!!!!

[Graham Butcher]

46 minutes ago, J.R. said:

I believe that you have the full Climatronic system, does it have individual temperature settings for driver & passenger?

 

I am assuming that they were both turned up to the same temperature, there are temperature sensors in the heater pipes, one of yours is probably not giving the true reading so the flaps are doing the wrong job.

 

VCDS will display the readings from all the sensors and the operating angle of the flaps compared to the commanded angle, if the flaps are working properly then the temperature sensor readinsg should be the same for both sides (both set to the same temp) if they are different you just have to work out which is the implausible reading and replace the sensor.

 

I bet you were looking for an excuse to remove your dashboard!!!!!

Yes, it is the full climatronic system with controls for both front seats and yes, both were set to the same temperature as I had the sync button switched on. If I plug the VCDS in, I take it I need to interrogate address 08, correct?

 

The photos I posted earlier, the first 3 are for the front, 1st photo is both set at 22C, 2nd photo is with both set to HI and the 3rd is with on LO.

 

If you're correct and the sensors do not agree, do I take it that I need to remove the dashboard in order to gain access to the sensors then, hence your last  point regarding removing the dashboard, I hope that is not required?

Edited 18 July, 2023 by Graham Butcher

[Graham Butcher]

4 hours ago, Graham Butcher said:

Should I get some sort of signal when the reset request is accepted? If so what is it?

 

6 hours ago, numskull said:

You could try a reset, Graham: you do this by holding the auto and face vents switches down together for 30s or so. 

Is what you was thinking of, the face button and the A/C together briefly and then the 2 LEDs start flashing and then seconds or so later the calibration is finished?  

 

[numskull]

Yes, give that a go first. Try the second if that doesn’t improve matters.

[Graham Butcher]

4 hours ago, numskull said:

Yes, give that a go first. Try the second if that doesn’t improve matters.

OK, I just have dropped SWMBO off at her place of work and returned home so I gave that a go and it really seems to have made a massive improvement already and I can now feel hot air coming from all vents when I set it to HI and when I set it to LO I can feel the temperature drop instantly and if I turn the A/C on it drops even lower, equally, with A/C on, set it HI and the hot air is emitted instantly (because the engine is already warm).

 

Just going to have my breakfast now and I'll repeat the test with temperature probes and meters and see how balanced the vents are, watch this space. 😀

Edited 19 July, 2023 by Graham Butcher

[J.R.]

Glad that the flapaerobics worked for you!

[numskull]

Nice one! 

[Graham Butcher]

51 minutes ago, numskull said:

Nice one! 

Great job, thank you for the input. As I expected, the two side vents are hotter than the two centre ones. I think it works on the same principle as air curtains on shop doorways, they are always the hottest to warm up any air coming via that way as it will be colder. Once the engine is upto normal running temperature, I now sit in the seat and toast quite happily, the same for all other seats in the car and the 3 zones can all operate independently just as it was designed to.

 

I wonder how the flaps came to be out of calibration in the first place?

 

Is it right that the two wedge shape vents on the top of the dash, above the side ones are not controlled? Are they part of the screen vents for demisting etc?

 

 

[numskull]

Correct. They’re only at full tilt when you select “Max” on the central dial demist button. Look for “Air Distribution Control” in the owners manual.