As I see it, there is absolutely no reason to complain about support of AC. At least there is a forum and support forms that you can use to communicate, even if it takes some time before you get an answer.
For comparison: Try getting an answer from Asus! (and there are more companies like that). They NEVER answer any mail or support questions, even if you have a big issue.

Remove the yellow cover at the back from your pump. Use a slotted screwdriver, insert it one after another into the leads for the base-plate and turn it a little bit. Aftwerwards you can easily remove it.

Take a look at the lower right. There you will see a 2-pin connector for the internal temperature sensor. Above you will see a small diode, above this you will see a pair of diodes. This pair of diodes should have a yellow ring. If one of them has a black/brown ring it has been damaged due to an overvoltage or short circuit. This normally only happens when the USB cable was plugged in the wrong way.

That's a good tip ... I will have a look in a few minutes (better switch of the PC first)
Just found out my mobo does not have a parallel port ... so I can't use the flash cable.
I'll check the diode now and will ask for support if it is broken ... (perhaps spare parts can be ordered).
I presume this must be the case as I probably did wrongly wire the USB in at least one occasion.
It would explain why there is no communication whatsoever, but I'll let you know in a few minutes.

OK. I've had a look (and took a picture, see attachment).
The pair of diodes that you've mentioned both seem to show a yellow band.
I guess now all I need to do is find another PC (with Parrellel I/O port)
drag it nearby this PC and try to connect it with the pump to flash it.

Sorry for the double post, but I have an update on my situation ...
I dragged the 2nd PC in my thouse from the livingroom to the attick, where my watercooled PC is located.
The 2nd PC has a LPT1 gate at the rear (unlike my own motherboard) and enough empty internal USB connectors.
But when searching for the pump with the flash-software ... No pump is found on any channel. Also the USB is (again) not detected at all (and this is NO Asus mobo)
So I can only conclude that the communication with the controller of my pump is completely dead.
I probably killed it when the usb was wrongly connected at one of the first attempts to connect the pump to the mobo.
The pump seems to work autonomeous though, so I still have cooling, but no controll.
Does anyone (Shoggy ?) know if it is possible to order a replacement electronics part ?
(I looks like it would need only a very limited amount of soldering)
In that case I may not need to 'bleed' the liquid out of the system, which would be the case if I have to replace the entire pump.

Citation de "Top_Nurse"

I disagree about that statement. However, perhaps they tire of people who don't want to use the search function. A lot of technical information is available on this forum and elsewhere (bit-tech, [H]ardForum, WizD, and other English speaking sites.

How well do you think support at Swiftech would be in a German speaking sub-forum? IIRC, there are only a couple of guys at AC that are able to converse fluently in English. And they all have regular jobs at AC that they do from 9-5 as well.

I currently have a post here as well that hasn't been answered, but considering what is going on I really didn't expect an answer till next week sometime. Now if I was in a hurry (and I already had the parts) I would just plug it all in and find out for myself.

I also sent in a request for price and delivery to AC Berlin for a few hundred Euro's last week and didn't even dream I would get an answer back till next week.

Top-Nurse, I agree with you that people should use the Search-function more, unfortunately that's the problem with a lot of people on the internet.

However, I must also stress out that after-sales services is a vital part of conducting business (any kind of business, for that matter), so offering proper support to customers and potential new customers is an absolute must, it cannot be ignored !!! And let's not forget that most people on the internet use English as primary language of communication, so English support should be a priority for all businesses that offer products or services on a worldwide scale (like Aqua Computer).
It is possible that other websites also contain some important information about AC products, but let's not forget that most people turn to the official source (in this case : this AC website and forum) whenever they need information on one of the AC products. So it's important that AC tries to have all the necessary information about their own products on their own website, and presented so that people can easily find it.

What I must also add in the case of Aqua-Computer is the fact that the AC website is a little mess in terms of support, here are some examples :
(1) Download pages containing links that download incorrect files (i.e. : not the file specified in the description) that don't even get updated after someone reports this issue (!!!)
(2) lack of a decent FAQ, especially an English version of it
(3) absence of proper connection illustrations (basic and advanced), including setups with multiple loops

As you say :

Citation

And they all have regular jobs at AC that they do from 9-5 as well.

Then they should spend some time during office hours to help customers, or hire someone extra personnel to do this if they don't have time for that themselves (although it should be said that a business should always make time for helping customers). That's how they do things over here, anyway. In fact, that's how most people conduct business almost everywhere.
Example : if your car breaks down, you call the garage during office hours. What would you do if no one would answer the phone for several days or perhaps even weeks ?
Hopefully this example will explain what I'm trying to say here, I think that it's clear enough for everyone to understand the point I'm trying to make. And if not : being in business also means offering good solid customer support. Customer support is a vital part of conducting business, and so therefor a company should spend a significant amount of time dealing with customers.
Actually, I would understand if AC people didn't have the time to help customers after business hours (everybody has the right to a private life), but during office hours a company should be available for support questions.

Here are suggestions that Aqua-Computer should think about :
- treat customers with the proper respect, especially when they're having problems with their products (basic customer service behavior)
- add connection examples (basic and advanced) that cover ALL possibilities in terms of connecting all the equipment together (from single loop LC systems to complex multiple loop setups)
- read what the people write, and if necessary : react and/or solve the issue if applicable.
- sometimes a picture, diagram or illustration can say more than a thousand words

Note : I'm not suggesting that AC doesn't do any of the above suggestions, I'm just suggesting what AC should think about and perhaps see if they can implement it or improve it if it already exists in order to improve customer support. It's in the best interest of the company to try and bring the best possible support for their customers, and totry and find better ways to provide that support.
And when people offer suggestions then it's a good idea for the company to look at these suggestions, because they might contain some interesting things that can help improve things.

I agree with you. AC has people monitoring bit-tech, Wiz-D, XtremeSystems, and the [H]ardForum as well as here. However, the primary thrust of their support operations is via email. A telephone call works even better (call in the afternoon Germany time).

My new (replacement) controller board finally arrived today.
After installation to the pump there was good news and bad news.
The good news is that the USB now immediately was detected by windows, and Aquasuite also found the pump.
The bad news is that this new controller shows a continuous red LED and the pump is not running.
(also reported by the aquasuite)
I double-checked the pump-wire connections, but they were correctly placed and making good contact.
So unfortunately, I will have to RMA it (already filled in the form) and wait for ANOTHER replacement.
I replaced the controller board again with the original one, and now my pump works again (but without USB).
I do not seem to have much luck with my pump ...

Bummer on the board.

Ask them to physically check the board before they ship you another one. Was your replacement a re-worked unit?

I think it was a brand new one.
I am sure I connected the two pump-wires correctly as well as the molex and the USB-plug.
From the first moment I applied power the red-LED kept on burning, and did not extinguish (as happens normally with my original board when starting up the pump). The pump did make some very faint noises though, but it would not run.
I hope they can/wil replace it.
At least I know now that it CAN work, as have seen the USB work on the new board and the pump works with the old board.
Now it would be nice if this could be combined ...

<<<UPDATE>>>

Today I received my replacement controller board. And guess what ... Everything works !! Hurah !
Now I finally can enjoy all the cool stuff !!