Broken AC: Troubleshooting & Repair Tips

Hello everyone,

My brother owns a Skoda Octavia 1Z, manufactured in 2013, with engine code CFHC. Recently, the air conditioning system has stopped working. I performed an AC service on the vehicle to check if there was enough refrigerant in the system. The result: everything seems fine so far. The system is not leaking.

There is also voltage present at the climate compressor, as well as at the pressure switch. If I unplug the pressure switch, the fans start running. Is this normal? Now my question: Is the compressor defective? Based on my assessment, everything points to that...

Do you have any more suggestions on what else I can check?

I am very grateful for any suggestions.

Hello,

With VCDS, the reason for the air conditioning system being deactivated can be identified.

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 Rainer,

Thank you for your reply. Unfortunately, I don't have access to VCDS, but we do have an AVL tester.
Could you tell me which menu item (MWB) I need to go to in order to view various "as-is" conditions? Is there an overview of the menu items? Are they the same for everyone?

Here's what else I can tell you about the compressor: The pulley is rusty brown, and the middle screw (Torx size 30) seems stuck; I can neither tighten it nor loosen it. It looks like a portion of it might be protruding.

Basti1605 wrote:

There is also voltage present at the climate compressor.

Did you measure it under load (i.e., with the compressor attached)?
Have you ever looked at the pulley? Does the inner part rotate, or is it stationary?

Greetings.
Sure.

Here is the translation of the text from German to English:

"Guste" means "gust" in English. It can also be used as a verb, meaning "to gust."

guste100 wrote:

Basti1605 wrote: There is also voltage on the climate compressor. Did you measure them with load (i.e., with the compressor attached)?

No, only when the plug is disconnected.

guste100 wrote:

Have you ever looked at the pulley? Does the inner part rotate, or is it stationary?

As mentioned above, the pulley is rusty. However, it still rotates. I have a picture of it, but I can't upload it.

Best regards, Basti.

You probably also have a compressor with a driven disk. Check to see if it might have been triggered. There's a picture in my thread, which Rainer linked, showing what it looks like.

Sure, here is the translation of the text from German to English:

"VG" translates to "Very Good" in English.
Andreas.

Hello Andreas,

I now have a new compressor and will install it sometime this week. However, I have to wait until the flushing machine arrives at our company.

Here's what would be helpful for me to know: How can I tell from the outside whether a compressor is permanently powered or if it's a "regular" one?

What pressure levels should I expect? In other words, what pressure is likely at different times?

Thank you for your support!

Basti.

Hello Basti,

The friction disc appears to be intact. However, I'm surprised that the screw on the shaft is protruding.

You have a compressor that is continuously running. The cooling capacity of the compressor is controlled via a control valve.

Before you replace the compressor based on suspicion, I would recommend conducting a thorough analysis first. In the worst-case scenario, something else is faulty, and you'll have to evacuate the system again.

Therefore, it would be beneficial to examine the compressor's measurement data blocks and shutdown conditions.

Good luck!
Andreas.

Hello Andreas,

Which blocks should I focus on then?
As I mentioned earlier, I currently only have access to an AVL tester (which also displays the mean effective pressure), but I intend to purchase a VCDS for personal use.

I'm also surprised about the middle screw. Especially since it's not possible to tighten or loosen it.
Voltage is applied to the compressor and the pressure switch.

I really want to expand my knowledge about debugging climate models now.


Thank you for your help.

Basti.

If the system is actually filled as described above, I would simply apply 12V directly to the control valve and start the motor for a quick test without any diagnostics.

Either the cold air/refrigerant line at the expansion valve becomes cold within 1 minute, or everything remains warm -> replace the compressor and/or control valve.

Hello Basti,

It is important that:
- Error memory
- Compressor current
- Compressor load
- any existing shutdown conditions.
- Carefully check the pipe with your hand to see if it's cold, in order to rule out a faulty expansion valve/throttle.


Sure, here is the translation of the text from German to English:

"VG" translates to "Very Good" in English.
Andreas.

Hello colleagues,

Today was the day. I investigated the air conditioning unit. It turned out to be 100% the compressor. I did some more research and found that there are two common problems with this type of compressor. Either the three pins on the front of the drive plate break off (a designed weak point in case of overload), or, as in my case, if the center screw comes loose, the shaft inside the compressor shears off. This results in a loss of power transmission.

I would also take the compressor apart to examine it and see how it works inside. If you'd like, I can post some pictures!

So, the compressor is new, the condenser is new, and everything is working fine again.

I would like to express my sincere gratitude for your assistance and the numerous helpful suggestions you provided.

Best regards,

Basti.

Thank you for the feedback! Pictures of the inside of the compressor would be great.

Basti1605 wrote:

So, the compressor is new, the condenser is new, and everything is working fine again.

Why did you replace the capacitor? Or were you referring to the dryer?

Sure, here is the translation of the text from German to English:

"VG" translates to "Very Good" in English.
Andreas.

I replaced the condenser including the dryer (which was not a separate part that could be replaced on that model) because the vehicle had started losing refrigerant again since the last AC check. And I didn't want to start taking everything apart again in a few days .

I haven't disassembled the compressor yet, but I will definitely post pictures soon.

Best regards,
Basti.

Basti1605 wrote:

... (which could not be individually replaced in that model)...

VAG is just getting worse and worse. It's only a matter of time before you can't even buy motor oil anymore, and the entire engine will have to be replaced.