Climatronic Compressor Cycling Every 2 Seconds (Vento 97)

Hi.
While browsing these pages, I already came across a similar case from last year.
Now that it's warm again, I've noticed that the air conditioning compressor is constantly turning on and off. The magnetic switch is quite audible. The motor's performance is deteriorating, which can be quite unpleasant at medium speed while driving.
'With the ECON mode activated, or if it's cooler outside, there's no problem. The issue appears immediately after starting the engine (ruling out a potential overheating problem). The air conditioning system was recently recharged last fall.'
I also visited VW, and the friendly VW master technician showed a lot of understanding for my problem. However, I don't think I can expect anything other than high costs from them.

At the end of last year, I experienced a series of problems: TÜV inspection, timing belt replacement. Due to the new (correct) tension on the V-belt, the water pump failed, followed by the power steering pump (which resulted in a rather messy situation). All of these components are located very close to the compressor, and there are various sensors and other things in that area. I've already checked the cables and connectors, but you'd need an arm with a 3cm diameter to reach everything. It's possible that something might have come loose.
Upon startup, all the symbols on the display blink for 15 seconds, indicating an error. Unfortunately, I've only found error code output key combinations from various websites, ranging from 1998 to 1994. The control unit doesn't respond to these.
Does anyone know the correct keyboard shortcut to read the memory?
Sure, here is the translation of the text from German to English:

'Or any other tips?'
Sure, here is the translation:

'I would be very grateful!'

Greetings.
Thomas.

Hello,

I have the same Climatronic in my Golf. So far, I haven't found any key combinations to access the control unit data. Therefore, I assume that this function doesn't exist in this old control unit. So, you'll need to read the error memory with a diagnostic tool to find out why your air conditioning system is behaving that way.

My assumption is that the problem is related to insufficient system pressure.

Regards,

Andy.

My suspicion, based on my recent experiences, is that the problem is either with faulty pressure switches, or the system is overfilled!

For the Climatronic system with ECON (models 95-99), there is currently no known way to put the system into diagnostic mode, and many people have tried and failed.

Thank you very much for now.

I'll check (or have someone check) about the overcrowding issue. The system was installed last year.
It was refilled, but could not be sufficiently tested (at high temperatures).
Interestingly, this 'pulsing' effect only occurs during hot summer temperatures; now that it's a bit cooler, everything is fine. Cold air is also coming in. And, the control system isn't registering any errors.

Until then.
Thomas.

Interestingly, this 'pulsing' effect only occurs during hot summer temperatures; now that it's a bit cooler, everything is fine.

It's possible that your front fans on the capacitor are also not working correctly, or that the capacitor itself is heavily soiled.
This increases the pressure within the system, and the pressure relief switch shuts down the system for safety reasons.

Soooo.
Now the system is working again.
After it got so warm outside, as described, this error only occurred when it was warm. I was able to have the error codes read by a 'friendly' mechanic.

'Pressure switch for air conditioning - F129'

I went to VW today, and the first thing they did was measure the fill level. Instead of the expected 850g, the system contained over 1200g. This meant the system was overfilled.
That's it! Put in something new - play!

I had the air conditioning system refilled last fall at ATU in Düsseldorf, on Heerdter Landstr.
They probably filled it the same way as they usually do with coolant, until the level is visible.

OK - Thank you very much for the contributions, especially to Dan.jel --> 'Bullseye'

Greetings.
Thomas.

Thank you for the feedback!

ATU has been appearing more frequently in the 'accident statistics' http://www.cheesebuerger.de/smilies/verbluefft/7.gif.

CU Gremlin.

It happened to me with a VW!
(He was a very capable trainee, after all...)

I almost have to explain to him how to do troubleshooting.
He had the diagnostic device in his hand, and he was very surprised that I could already tell him what errors had occurred! *ggg*

But be glad that it was only an overflow, because everything else could be really expensive. (And that's how you know your system is sealed! )

Dan.jel wrote:

My suspicion stems from my recent experiences with faulty pressure switches, or the system being overfilled!

I completely agree.

After I bought my car, the system was filled with 970 grams instead of the expected 650 grams.
The consequence was that the fan was always running at the second speed, because the system pressure was too high due to the overfilling, and the pressure in the evaporator decreased due to the cooling.