AC Noisy After G65 Sensor Repair

Good morning from Berlin.

"My name is Stratos, and I've been driving an A3 Sportback TFSI, model year 2005, for about a year now. It currently has almost 180,000 kilometers on the odometer."

A week ago, I had the G65 pressure sensor of the air conditioning system, along with the associated tubing, replaced. To do this, the system was evacuated and then refilled after the repair.

Since then, I've been experiencing a speed-dependent whining noise as long as the outside temperature is below the set value of the climate control system. The whining stops immediately when the ECON button is pressed.

If you put your head under the hood towards the compressor, you won't hear any whining.

When the interior of the car has heated up throughout the day, and you start the engine, the air conditioning system kicks in powerfully without any extraneous noises and does what it's supposed to do: cool the air.

This morning, with an outside temperature of 15 degrees Celsius, I read the pressure value using VCDS (engine not running, just ignition on). The value for sensor G65 was 8.0 bar.

Now, firstly, I'm not sure if my measurements are accurate. If I look at the tables in the relevant technical article, the pressure should be around 4 bar at that temperature.

Did I measure something incorrectly, or is the system possibly overloaded, causing the compressor or some other part of the air conditioning unit to make a whining noise?

Greetings.

Stratos.

Hi,

The expansion valve (located on the firewall between the passenger compartment and the engine compartment) can cause noises.

Best regards, Rainer.

"8 bar at 15°C is definitely too much; the system is overfilled!"

Or had the engine been running previously, meaning there might have been residual heat in the engine compartment?

Hello,

The car had been standing all night. As I said, I only plugged in the VCDS today, turned the ignition on, and then read the corresponding values. I was actually expecting something closer to 4-5 bar.

If the facility is truly overcrowded, then in my opinion, it would have to be extremely overcrowded.

8 bar roughly corresponds to 35 °C.
As long as the temperature within the system is below this value, the refrigerant will condense, and the pressure will decrease. Even a small area within the refrigerant system that reaches 35°C would not cause a problem, because the refrigerant (like water vapor) always condenses at the coldest point, and therefore the temperature of the coldest points determines the system pressure (as long as there is still free volume).

If the pressure is actually 8 bar at 15°C, it would mean that the entire system is completely full of liquid refrigerant. If that were the case, there would likely be a loud bang when the system is first turned on. After that, the compressor would need to be replaced because it cannot handle liquid refrigerant on the suction side.

Nevertheless, it wouldn't hurt to initially use the Econ mode and have the pressure checked manually, at least with the help of a technician.

Greetings.
Guste.

Are these air conditioning units calibrated in any way in the workshops?
I would like to have the car inspected again at that location and ask the workshop to completely extract the refrigerant and then have it weighed again and refilled to the specified 520g.
It's not like the thing measures the distance to the moon. Before the repair, it definitely wasn't working properly, and I was told that it was missing refrigerant.
However, the system had already been inspected and refilled in February. But even after the repair, it seemed to be leak-proof at that time. At least, it maintained the vacuum.
Does the device also know how much oil, etc., is being added?

Quote:

At least she maintained the vacuum.

The system, however, does not contain a vacuum, but rather coolant and coolant oil.
Okay, I'm ready. Please provide the German text you want me to translate.

The amount of coolant to be filled and the type of coolant oil are entered into the maintenance device according to the manufacturer's specifications.

Typically, you receive a record indicating how much money was deposited. What information does it contain?

I just stood next to him and watched the process of fixing the air conditioner, and he explained it to me. Let's see how it looks tomorrow morning.
The refrigerant levels and pressures were definitely okay.

Bis jetzt *Daumen drück* scheint wieder alles okay zu sein. No more whining.
Whatever didn't work when filling it up after the repair.
Thank you for your answers and suggestions.