Climatronic Not Cooling? Troubleshooting Guide.

Hello fellow mechanics,

At the beginning of the air conditioning season, I unfortunately discovered that the Climatronic system in my Golf IV Pacific, manufactured in 2003 with engine code AXR, is no longer cooling.

Troubleshooting steps performed so far:
- Coolant level is within the normal range and has been checked by a climate control technician.
- Error memory read, OK, no errors.
- Sensors checked, they appear to be functioning correctly; none of the sensors are showing implausible, negative values.
- Fuses checked.
- The air conditioning compressor is directly powered by 12V, the solenoid valve switches, and the system cools.
- Measurements taken at the connector near the compressor showed 12V when the air conditioning compressor is turned off, as indicated in the diagnostic system.

Okay, and now I'm unfortunately stuck... There's 12V at the compressor, but it's not turning on. I suspect there might be a relay somewhere that's controlling the power to the compressor, but I can't find it. Does anyone have any ideas?

Thank you very much, and greetings from Darmstadt.

Holger.

Hi,

Okay, but directly on the climate compressor (cable length approximately 20cm), there's a 2-pin connector.
"If you apply 12V to it, the magnetic coupling engages and it cools (yes?), but you also wrote that 12V is present in normal operation, but the coupling isn't engaged... so what's going on?"

12V, measured against what?

Best regards, Rainer.

Hello Rainer,

"I measured the voltage at this exact connector, or applied the 12V to it. That's exactly what I don't understand. The connector itself looks fine. Could it be that the voltage drops under load?"

Regards,

Holger.

Hello!

That would be possible if you have a very high resistance somewhere. Take a look at the fuses on the battery. And try removing each one individually. Mine were regularly corroded before I applied a thin layer of copper paste to them... The air conditioning also stopped working, just like in your case.


Best regards,

...or a bite from a weasel into the cable.

Hello,

Okay, I've now swapped all three green fuses and tried to clean the contacts (but I will replace them with new fuses later).
The magnetic switch is now turning the AC compressor on (and off). However, it's doing so at a frequency of approximately 1 Hz when the car is idling. I'm not sure if this is normal (I haven't paid attention to it before). I'll now take another test drive and then check the temperatures (I believe the evaporator should be at 7°C).

Regards,

Holger.

"No, that's not normal, actually. There must be some kind of electrical fault. It's best to replace the fuses. And also check the fuse holder itself. The contacts there might be corroded as well!"

Okay, I've found the errors...

After replacing the fuses, which didn't solve the problem, I suspected the control unit for the fan/compressor. This unit is attached to the longitudinal beam, underneath the battery holder. I planned to swap it with the control unit from our other Golf, using a Cimatronic device, tonight.
There are two connectors on the control unit. One has wires from the control panel (with a smaller cross-section), and the other has wires leading to the fuses for the compressor/fan.
Lo and behold, the cable to the fuse (terminal 30) was damaged and almost completely corroded. A few strands were still intact.
Ich habe den beschädigten Teil rausgeschnitten und das Kabel wieder ordentlich verbunden. Okay, let's go again.


Thank you again for your help with troubleshooting!

Regards,

Holger.

Great! Thanks for the feedback! Then the sun can shine again

Dirk.