Touran AC Not Working? Troubleshooting Guide

The sun is shining - but the air conditioner isn't doing its job .
Visual inspection reveals no clues. The compressor is running.
All connections are fine - Now let's check for errors...
BUT: VCDS reports no errors.
How can I narrow down the source of the error?
Why, for example, is the actual compressor current value not being displayed?

I once ran a scan and have attached the resulting file.

Do you perhaps have a suggestion for me here?

Best regards, SL.

Please update to the latest VCDS version (14.10.2): https://shop.dieselschrauber.de/account.php

Possibly, the actual value will already be displayed then.

Best regards, Rainer.

Okay. Thank you. I'll do that right away.

The actual value is still not being displayed.
But well, the main problem is that it's not getting cool enough.

The (calculated) compressor load of 4.6 Nm is close to zero. Therefore, the control system assumes (and rightly so) that the compressor is not running.

The reason for this should become clear from the shutdown conditions. What do those conditions indicate?

However, I am admittedly puzzled that the compressor's current draw is still above 0A.

I think the system is probably just lacking enough refrigerant.

Here are the specifications for a comparable air conditioning unit, model PA 3C, manufactured in 2007.

With the vehicle at ambient temperature (approximately 30°C), the refrigerant pressure was approximately 8 bar with the air conditioning system still turned off.

Thank you for the reference values!
I've now experienced the worst-case scenarios. The system is running, but...
"but it's not really getting going." I'm planning to go next week instead.
Let me take a look at the refrigerant. I'll report back later.

-Andreas

Just came back from the "climate control service." They removed 470 grams of refrigerant and 7 ml of oil, and then added 525 ml of refrigerant and 15 ml of oil. The climate control system still isn't working.
The mechanic said, "The compressor is not working."
"But how can the evaporation temperature then be 14°C?" I asked.
Daraufhin hat er das "Anforderungsignal" unter Last gemessen. Die 12 V brechen unter Last zusammen. What now?
Please provide the German text you would like me to translate into English.
Is it the case that in the Touran, the supercharger is constantly running and that the pressure build-up is then regulated via an internal control system?
Please provide the German text you would like me to translate into English.
I'm not sure where to start looking right now...

Hello!

It depends on what kind of "load" was electrically connected. I would simply measure it in parallel with the control valve. However, it's a PWM signal.
If in doubt, re-wire the cable using temporary connections to check for contact resistance.

So, the mechanic connected an H7 bulb as a "load" and measured the voltage in parallel with it.

Nonsense. An H7 bulb has 55 watts. That corresponds to approximately 5 amps. The valve is activated with a maximum of 0.6-0.8 amps when the compressor is at FULL LOAD (or that current flows then). The control unit probably already thought it was heading towards a short circuit. Maybe ask someone who knows about this.

You wouldn't believe what some German repair shops sometimes have on offer.

My problem is finding someone who really knows what they're doing. I've unfortunately had some bad experiences in the past. That's why I try to understand the issue at least somewhat before going to a workshop – if I can't fix it myself. Otherwise, everyone just guesses and uses half-knowledge, and in the end, I have to pay the bill...

"As you write, I could measure the voltage while the cable is connected. What are the specific measurement characteristics of a PWM signal? Can this be measured with a standard multimeter? Isn't it just a rectangular wave?"

You won't be able to measure that with a standard multimeter. At least, not in a meaningful way. The frequency is 500 Hz.

My friend has a digital oscilloscope (ARM DSO203 Nano).
I should be able to measure that with this.
Please provide the German text you would like me to translate into English.
I'm still a bit shocked... someone from the workshop was just telling me that...
that the control signal is not arriving and that I'm facing a very long search.
...can be adjusted in the workshop after encountering any errors.

-Andreas

... and it seems that important know-how is lacking.

Often, the pressure regulating valve in the compressor is defective! You can buy it separately at certain automotive parts stores.