PTC Air Heater Questions: Z35 Model & Controller

Defective electric auxiliary heaters (which heat the intake air in the climate control unit, not a separate heating device) with non-erasable errors have been discussed here before, see for example https://community.dieselschrauber.org/en/viewtopic.php?t=26006 and especially https://community.dieselschrauber.org/en/viewtopic.php?t=28328..

I mean the auxiliary heater (Z35) with PTC element, see the error message below - not a dedicated auxiliary heater. I have the version with control unit (J604), which was installed in the Passat 2006 B6 up to week 43/06.

The usual solution is found here (from the second of the links mentioned above).

Quote:

Helping to fix the issue was resoldering the five larger resistors on the circuit board; these likely had cold solder joints.

The heater has been working again since then.
However, I have also read that the control unit is often defective as well.

What I find surprising about the solution described above is that the device heats up during actuator diagnostics, but not otherwise (Is it not being activated? That would actually suggest a control unit defect, especially at low temperatures).

Therefore, two questions, before I take this thing apart (which is supposed to be quite fiddly):

- If the control unit responds, outputs values, and performs an actuator diagnosis (see image below), it's hard to imagine that it itself is faulty, right?

- Why does the auxiliary heater activate during actuator diagnostics but never at any other time? (Temperatures are below zero. An error message is also present.)

It's more of a theoretical question, but I don't really understand how it would work through diagnostics, but not when using the standard control method.
(if this is the case, but if not, would it be a problem with the control unit rather than one of the resistors that needs to be soldered?)

Are the values shown in the image actually realistic? (I had also read about higher performance and larger currents, but the actuator diagnosis only had one option with the result shown.)

Quote:

Address 7D: Auxiliary heater Label file: DRV\1K0-963-235.lbl Part number SW: 1K0 963 235 E, Hardware part number: 1K0 963 235 E. Component: PTC Element 0404 Revision: 00800000 Serial Number: Operating Number: WSC 00000 000 00000 VCID: 2D56C4E2B48F672E11-8078 "One error found:" 00361 - Heating element for auxiliary heater (Z35) 014 - defective

Quote:

Advanced identification. Serial number: Identification: BEB-001 Revision: 00800000 Date: 06/06/06 Test item number: 2100. Manufacturer part number: 4072. Software: K0404 Miscellaneous: Hardware number: 1K0 963 235 E. VCDS Info: VCID: 2D56C4E2B48F672E11-8078 Label file: DRV\1K0-963-235.LBL

Error messages (English) for Ross Tech error code 00361: http://wiki.ross-tech.com/wiki/index.php/00361

Speculation:
In actuator diagnostics, the transistor is simply switched on and off.
Under normal operation, parameters such as the voltage supply, power consumption, or parameter 42 are monitored. If only the latter is defective, then the actuator diagnostics and normal operation will fail.

Similar to cheap LED light bulbs (with insufficient power consumption) in a car: they illuminate for 3 seconds and then switch off, being registered as defective in the error memory. So it works, but the parameters for normal operation are not correct.

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."

Quote:

Why does the auxiliary heater activate during actuator diagnostics, but never at any other time?

A theory I recently read (on an English forum) suggests that the total heating power is likely to be 1000 watts (with a current of 70 amps).

Quote:

A heating power of 600 watts indicates that only 2 (out of a total of three) heating elements are functioning correctly. Probably, this is why the entire heating unit is identified as defective by the control unit and not used.

Maybe it's just a theory, but it sounds pretty convincing to me (as an answer to my original question).

And please answer my further question about whether the power shown in the actuator diagnosis image is likely correct (it's currently at 2/3 of its rated power).

So, it's probably the recommended approach to resolder those five resistors on the circuit board.

While I've done some soldering and crafting before, I haven't worked with any surface mount devices (SMDs) yet – those are the components that are soldered directly onto the board from above. I'll need to do some research on that first.

And I'm not really looking forward to the expansion either.

Quote:

During normal operation, for example, the voltage supply, power consumption, or parameter 42 are monitored. If only the latter is defective, then the actuator diagnostics and normal operation will fail.

Yes, something like that, that makes sense.

Siehe meine Antwort an mich selbst   von eben, welche sich mit Deiner überschnitten hat. GlThat's an interesting thought.

Best regards!

I'm experiencing the exact same error.

- Heating element for auxiliary heater (Z35).
014 - defective
- Diagnostic interface for the data bus (J533): No connection or incorrect configuration.
005 - Basic settings / Adaptation.


I bought a used "tested" item from a seller on eBay and installed it today, but it has the exact same problem.

After installation, I activated the auxiliary heater using the actuator diagnostics function, and it only reached approximately 600 watts before slowly decreasing to around 300 watts.

Has anyone had any success with soldering or using an oven yet?

Praktische Erfahrungen an genau dem Steuergerät habe ich noch nicht. But generally:

SMD soldering isn't rocket science. A reasonably fine soldering tip with a moderately powerful soldering iron should be sufficient for this. In this case, we're even dealing with power resistors, so the wattage is more important than having a very fine tip.

If you have a DSLR or another camera with reasonably good macro capabilities, you should be able to see the cracked solder joints. If you post a picture here, we'd be happy to help. You should still have the old control unit lying around somewhere.

PS: The air heater consists of three heating elements. Similar to the Golf 3 era with its three glow plugs in the water circuit. Depending on the voltage and temperature, either the low setting (one heating element) or the high setting (two heating elements), or both settings (all three heating elements) are activated. Based on what I'm reading here about the problems people are experiencing, it seems that the low setting (the single heating element) is always the one causing issues.

That explains why the control unit sets the error code, but still gets warm during diagnosis (thanks to the large heat sink).

So, it only needs to solder the small step in place.

PS 2: In the Passat 3C, the PTC heater was only used in the first few production years (I believe 2006 and 2007). Afterwards, the three heating elements were directly controlled by external relays (I think from 2008 onwards). They probably realized that a power control unit wasn't necessary for such a simple heating element. It was likely intended as a fast-responding PWM controller, but it was never implemented in that way.

Regards,
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."

Thank you very much, Guste, for the detailed explanation and assistance.
This weekend, I removed the auxiliary heater from my brother's car (same make and model) and resoldered the five resistors.

Before the upgrade, it had a maximum output of 300 watts during the actuator diagnosis test.
First, I put the circuit board into the oven at 180 degrees Celsius for about 10 minutes.
After the oven, it went up to a maximum of 700 watts, but still displayed the same error message.
After further modification, the five resistors were "resoldered" by keeping the soldering iron on each resistor for approximately 5-8 seconds and touching the tip to the connection point. However, there was still an error, and the output was limited to 700 watts.

"How do I know which is the small step and which is the large step on the circuit board?"

abicim wrote:

First, I put the circuit board into the oven at 180 degrees for about 10 minutes.

"Uh, that's quite a crude method. I'm not sure if that was the right approach."

Most electronic components are not designed for this temperature. Typically, they are specified to a maximum of 125°C in the automotive sector. Of course, this temperature can be exceeded during soldering, but 10 minutes is significantly longer than the soldering profiles I am familiar with.
In addition, soldering is typically done with a peak temperature of approximately 240°C. In short: The time may have been too long for some components, and the temperature may have been too low for the solder.
In mass production, a proper soldering oven follows very specific soldering profiles. For example, it might heat up to just below 200°C within 2-3 minutes using a precisely defined ramp, then quickly reach a temperature of 240°C in less than 60 seconds, and then cool down again.

abicim wrote:

(...) However, it still has flaws and only works up to 700 watts. How do I know which is the small step and which is the large step on the circuit board?

To do that, we need to examine the layout of the traces. Please post a high-resolution and clear photo, and then we'll have a chance to help.

As mentioned before, it's possible that you may have already killed something in the oven.

Hi,

Quote:

Furthermore, soldering is typically done with a peak temperature of approximately 240°C. In short: The time may have been too long for some components, and the temperature may have been too low for the solder.

The oven probably caused more harm than good; electrolytic capacitors in particular don't like prolonged exposure to high temperatures. At 180°C, with typical lead-free solder, very little melting is likely to occur.

I recommend soldering the connections manually using a soldering iron.

Best regards, Rainer.

Hello everyone,

I wanted to give a quick update: I didn't have the professional equipment needed to potentially solve this problem myself. After many unsuccessful attempts, I sent the auxiliary heater to ecu.de for repair. They repaired and tested the circuit board and sent it back. The whole process cost €145 due to some extra work (resulting from the failed attempts).

After that, I installed the auxiliary heater today and first read the error memory, and lo and behold, there were no more error messages stored.
Then the engine was started, and the actuator diagnosis was run. As can be seen from the Screenshot, almost 1,000 watts were reached. I also immediately felt the warm air flowing out.

Thank you to everyone for your support.

Best regards, Orhan.

Thank you for the feedback!