Climate-Friendly ASZ: Agile Solutions!

Hi,

Today I noticed that my car's air conditioning system accelerates much faster when set to "Auto" compared to when it's in "Eco" mode. There's a noticeable difference of several seconds (roughly measured) between 120 km/h and 180 km/h.

How is that possible? Shouldn't it be the other way around?
The instantaneous peak power consumption values from the MFA are identical, so they aren't very useful for a rough estimate of the injection quantity.

Roger wrote:

I noticed today that my car's air conditioning system, when set to "Auto" on the Climatronic, accelerates much faster than when it's in "Econ" mode. There's a difference of several seconds (roughly measured) between 120 km/h and 180 km/h. How is that possible? Shouldn't it be the other way around? The peak power consumption values from the MFA are identical, so they are not very useful for a rough estimate of the injection quantity...

Well, then you'll have to delve deeper and log the fuel injection amount.

Perhaps the climate control software is designed in such a way that it deactivates the compressor (for a longer period) when set to "Auto" mode and during full-throttle acceleration?

Hello Ulf,

Well, in "Econ" mode, the compressor should ideally remain off for a much longer period .

I'm thinking more along the lines of coolant temperature, which would be lowered by the immediately starting cooling fan. Is there a kind of "soft" emergency mode that activates when the coolant temperature is too high – but still below the warning threshold – where no error code is stored, but the performance is reduced?

Logging will resume no earlier than next weekend.

Okay Roger, go ahead.

Unfortunately, I couldn't detect any differences with ASZ ERF, both with and without the air conditioning on. I'm not sure to what extent the coolant temperature should be considered. The assumption that a "higher" performance curve is used when the air conditioning is turned on to compensate for power consumption hasn't been definitively disproven. If the climate control is set to "Auto" and the compressor shuts off at full load, as it does in my case, it's possible that this higher performance curve remains active, which could potentially explain the increased power output.

As I said, this is speculative.

It also reacts much more spontaneously even at partial load, and it doesn't require full load to achieve this.

I'm thinking more along the lines of coolant temperature, which would be lowered by the immediately starting cooling fan. Is there a kind of 'soft' emergency mode that activates when the coolant temperature is too high – but still below the warning threshold – where no error code is stored, but the performance is reduced?


Hm, mal geloggt, was die beiden Kühllüfter an Strom ziehen? Die geringe Mehr-Kühlluft frisst der höhere Strombedarf des Generators wieder auf. MinSure.

Do you still have a magnetic clutch on your AC compressor, or have you already switched to the one with a wobble plate?

The warning threshold for the Golf 4 TDI, to my knowledge, is >110°C; before that point, the engine control unit (ECU) does nothing, and only mechanical/thermodynamic values play a role.

Could it be that the engine receives different mapping parameters when the air conditioning is activated?

Other parameters are likely not affected, but the fuel injection quantity is probably slightly increased.

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@ulf:

I've been monitoring the shutdown condition of the air conditioning compressor on channel 19 for a few days because the outdoor temperatures were close to the threshold for low-temperature shutoff.

There were two interesting effects observed:

- The compressor runs even at an outside temperature of only +2 degrees Celsius for more than 20 minutes and only shuts off when the temperature permanently reaches .5 degrees (shutdown condition 14, "Function of evaporator temperature"). At a traffic light, it even restarts at .5 degrees (shutdown condition 0).

- The control unit (CT) briefly deactivates the compressor during rapid acceleration with more than approximately half throttle (deactivation condition 12, "Engine Control Interface").
At approximately ,5 degrees Celsius ambient temperature, a situation can even arise where the compressor is switched off during constant speed driving, then switches back on at the next traffic light, and is subsequently switched off by the Motronic system when starting, only to be switched off again immediately due to low temperature (14 -> 0 -> 12 -> 14).

There must be a wobble plate in the compressor, because all of this happens smoothly without any noticeable jolts. Without the display, it wouldn't even be noticeable.
I think a magnetic coupling wouldn't be able to handle this control scheme for very long either.

Unfortunately, I haven't been able to log anything yet, but the more agile behavior described at the beginning hasn't changed regarding how the car operates.