thjohnson58

Please help I have:
2014 A4 B8 33K miles
As far as I can tell I have the MMI 3plus. I have the color screen with the joystick built into the large button on the console which I was told meant the 3 plus. I have a subwolfer. I can enter an address in the nav system using voice. Everything things works but no sound. With any input no sound. It works for about 10 seconds an hour. NAV is fine, telephone seems fine, cd works but no sound. It makes a clicking noise through all the speakers when its not working and as far as I can tell it never stops. Can anyone tell me where the amp is. It is NOT in the left rear quarter in the trunk. That is the sirus receiver, nor is it in the right rear of the trunk, that is a module that runs part of the car.
Any help is greatly appreciated. This car is in mint condition and its driving me nuts.

thjohnson58

So it turns out this is a Harmon Karden amp 4G00350826G. Can I get it repaired? Can I buy another amp that is 3Gplus to replace it?

SMac770

I believe the mini-joystick is on all 3G and 3G+. You have a US 2014; so if you have MMI, it's 3G+. (2009, 2G, 2010-2012, 3G, 2013-2016, 3G+)
HK amp? You mean B&O amp?
The part number is not functional. It starts off fine, 4G0 035 is the start of the part numbers for the head units. But not the amps.
The amp is certainly behind the left cover in the rear cargo area. It's the only place the amp is located in the B8. For the MMI cars, in the rack in that area, the radio unit is on the bottom, and the amp is on the top.
Your amp is going to be either 8R1035223A if you have the standard 10 speaker system, or 8T1035223A if you have the B&O 14 speaker system. Both have the subwoofer on the rear deck. The difference is the two door tweeters in the front and the two mids on the rear deck.

thjohnson58

You are correct on the location of the amp. It says Harmon Becker Automotive Systems part no 4G0 035 082 G. Made in Germany. Other numbers are K56JBT 7827493$. The case has no markings on it. Just a steel case. But the really good new is I knew it was a heat problem but did think I could get this lucky. Just a bad fan. Right below in the picture is the heat sink that cools the drivers. The fan sits

Only marks

Bad fan
in that entrance and it was bad. The original is 2 months away in China but Mouser Electronics had a Sanyo replacement with more cfm and lower watt requirement. 12 bucks plus shipping.

thjohnson58

Kinda strange. Thats the only box in that corner. I have the plastic tray but the top is empty. I definitely have MMI. That has to be some kind of amp with heat sinks that large and heavy. I don't have any extra plugs either. That the reason I was so adamant that my amp wasn't there. I software code on the screen is MMI 3Gplus.

Kris Hansen

Have you scanned for faults? I had that happen once in an allroad press car, and there was just a fault. Once I cleared it, everything was fine.

thjohnson58

Yes but I would have to go back and look again. It was a communication error and I did clear it. And I rebooted the MMI several times. I am pretty sure the MOST system went down was as when there was no sound I also lost MMI display in the dash. Not on the MMI screen and the NAV continued to work without sound. It is definitely a heat issue. All sound works when the car sits overnight for a few minutes at startup. Then quits and tries again once its cools and works for around 10- 15 seconds then repeats the cycle. Here in Fl that trunk gets pretty warm during the day. We did have a few and the sound worked much longer in the morning on those days.

This fan is bad. You mentioned this was the radio unit?? Only the radio unit?

SMac770

Interesting. It seems that the standard sound system for MMI 3G uses an integrated radio/amp unit, while it was a separate amp unit in MMI 2G. The B&O sound system uses a separate amp in both MMI generations. So it makes sense that you have MMI 3G(+) and no amp unit, if you have the non-B&O sound system.
The unfortunate part of that is if you replace the consolidated unit with a replacement, I suspect you might run into component protection. And need to go to the dealership to have them address that. They would likely bill you an hour of labor.

So you replaced the fan and still have shutdown, or all is good now?

thjohnson58

Not sure yet. I will have the fan in a few days. I do know that the heat sinks for the amp drivers are supposed to be cooled by this broken fan. Will post when I have the new one installed.

thjohnson58

Well no joy. I replaced the fan and it had not effect. I did notice on the screen when I have the tone controls up the bass and sub indicators take turns flashing as if the cursor was on them corresponding with the clicking noise I hear from the speakers. You know I bought this car previously owned by a elderly lady snowbird who drove it 3k miles a year. I am 60 and it now has 30K on it so its not like it been running at 100% for the last 4 years. This should not have happened. I don't really know where to turn now.