Climate control not cooling, error memory cleared

Hello.

The air conditioning hasn't been working since yesterday.
The pipes from the air conditioning unit remain cold, and I don't hear the compressor kicking on.
The climate control system hasn't been serviced in the last 3 years.

Audi A6 4F, manufactured in 2009, 2.7 TDI engine.
How can I check if the compressor is faulty or if there is too little refrigerant?
Surely there should be an error message appearing, right?

Best regards,

Hi,

By clicking on the label file displayed in the top left corner, you can view and check the compressor's shut-off conditions.
According to your Screenshot, there is pressure, but is the compressor shaft actually rotating?

Best regards, Rainer.

Glatze wrote:

How can I check if the compressor is faulty or if there is too little refrigerant? Surely there should be an error message appearing, right?

You can only check the refrigerant level with a climate control service device. The air conditioning system is only very superficially monitored via the OBD (On-Board Diagnostics) system. I wouldn't place too much importance on any error messages that might appear there.

Your compressor will be of a newer design. Therefore, you should first check if the driven disc is still being engaged by the shaft.

Otherwise, you can look at pictures in my old post to see what the disc looks like when the rivets are sheared off.

Hello,

Okay, thank you. From above, it's hard to tell whether the wave is rotating.
I have to go on stage first.
I was connected to the car with VCDS again.

Adjusting values while switching on.
Besides the pressure, which can range from 2.6 to 29 bar.

Please see the attachment.
The pressure gauge occasionally drops to 4 bar when the engine is idling.

Best regards,

The refrigerant pressure seems too low with the system turned off.

I would first make sure the correct amount of filling is used before continuing the search.

Hello.


ok danke
I'll do that sometime.


Best regards,

Hello.

Okay, so I got an update. There was only 45 grams of refrigerant left, so we topped it up, and now we're going to see if there's a leak anywhere.
According to the workshop, too much had been removed.

Best regards,

Glatze wrote:

Hello. Okay, so here's the update. There was only 45 grams of refrigerant left, so we topped it up, and now we're going to see if there's a leak anywhere. According to the workshop, too much had been removed. best regards

Up to 100g per year is acceptable. If you know when the air conditioning system was last serviced, you can calculate whether the refrigerant loss falls within that range based on the amount missing.

Hopefully, contrast agent was used so that you can quickly locate any leaks if there are any.

Quote:

So, there was only 45g of refrigerant left, we topped it up, and now we'll see if it has any leaks anywhere.

Don't hit me for this... but the current pressure readings when the compressor is on or off might be interesting as a clue.

Given the current outdoor temperatures, I estimate the pressure to be around 8 bar with the compressor switched off, and >15 bar with the compressor switched on.

It sounds like that was a poorly run operation. They filled the system with refrigerant first and then tried to find leaks afterward. Before filling, you should always check for leaks using nitrogen (with 25 bar of overpressure) and a small amount of refrigerant with soapy water, or an electronic leak detector. Alternatively, you can also add a dye and use a UV lamp to locate any leaks.

Hello.

Just so you know, I've had the car for 4 years, and I haven't had any AC service done on it. I don't think the previous owner did either.

Contrast agent was also added to the mixture.
Of course, I immediately checked and documented the pressures.
The outside temperature was 17°C.

Please see the attachment.

Best regards,

Hello.

The climate control is not working again; there's an issue with the data in the non-volatile memory (FS-memory).

00256 - Sensor for refrigerant pressure/temperature (G395).
004 - No signal/communication.
Environmental conditions:
Error status: 01100100
Error priority: 3
Error frequency: 1.
Lost Count: 48
Mileage: 274,900 km
Time: 0.
Date: 2018.02.08
Time: 08:40:48

According to measurement block 51, the pressure is 51 bar.

Is the sensor defective?

Glatze wrote:

Hello. The climate control is not working again; there's an issue with the data in the non-volatile memory (FS-memory). 00256 - Sensor for refrigerant pressure/temperature (G395). 004 - No signal/communication. Environmental conditions: Error status: 01100100 Error priority: 3 Error frequency: 1. Lost Count: 48 Mileage: 274,900 km Time: 0. Date: 2018.02.08 Time: 08:40:48 According to measurement block 51, the pressure is 51 bar. Is the sensor defective?

Hi,

Defective sender or its wiring. Warning: The air conditioning compressor will never turn on below ~5°C.

See also:
I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

Best regards, Rainer.

Hello.

ok danke

With a temperature of 5°C, it is known that...
I will double-check it and, if necessary, replace the sensor.

Best regards,

Okay, it's happened to me too. Yesterday, I drove to university, studied, and the car was parked in direct sunlight all day. When I got back in, there was no cold air coming from the vents. At home, I logged the following values using VCDS: (see attachment).


Approximately one year ago, the air conditioning system was serviced. The car has always cooled down properly, so I rarely set it below 21°C. Using a diagnostic tool, I tested both fans, and they are working perfectly. There are no error codes stored. The pulley is rotating, as far as I can tell from above. Both refrigerant lines feel extremely hot to the touch.
I'm not sure what to do next, and we're now experiencing temperatures above 30°C.

dieselfreak89 wrote:

Both climate control pipes are burning hot to the touch.

The line to the expansion valve should be warm. The line to the compressor should be cold.

Was bedeutet das?

I'm betting on the expansion valve.