My q7 keeps blowing the 10A air conditioner, front fuse on the passengers side. It's in the top row slot number 10. I tried replacing the blower motor resistors and it did nothing. It's winter in Minnesota, so I'm not even using my AC. But when the fuse blows I loose my heated seats, my climate control, heat, everything tied into that system. The rear climate control system displays like normal. But can't get anything to blow air back there either. HELP! WHAT WOULD CAUSE THIS! I've only own the car a month and have nothing but electrical problems. Just want the heat to work so I can pass it along for the next gyt to deal with.

 

You won't know diddly about your car until you put a VAG-compatible scantool on the car, so it can speak VW to your German car and tell you what's going on with it under the skin...there are trouble codes stored that will point you at the problem. You have fallen into the classic Audi trap of not knowing what you bought and trying to replace parts on it you think may help that aren't actually broken, or necessarily even involved in the fault that is causing your problem. Buy a compatible scantool. If you desire to DIY this car, buy the Ross-Tech VCDS cable scantool setup and fix your issues w/o losing your mind or your $$ over it. If you aren't really a DIYer, at least get an OBD-Eleven basic module to use with a smartphone, so you can read the trouble codes easily, etc, and gain an understanding of what's going on with it, so you don't get taken advantage of. Really the car is not that difficult to maintain, but you've got to know where to start, and that always begins with a full diagnostic scan using a compatible scantool.

 

It actually could be something as simple as a bad relay, or eventually the HVAC blower motor does go out (often suddenly) since they run all the time. We don't know anything about your car's history, nor do you, so you've got to start with the dataset you can access. Once you get it fully scanned for trouble codes, you should be able to tell what is wrong yourself, or can leverage that info to then ask for educated help rather than simply throwing a dart at a wall blind-folded. These cars are fully networked and have a great deal of complexity to systems, so you need the proper scantool to act both as guide and advocate on your behalf, with the car's systems.

Older Q7s really are great cars for a DIYer, but not so much for the average used-car owner. Make no assumptions; always scan the car. Never throw parts at a problem on an Audi.

Hope you got a great deal on it, and gain a speedy resolution to enjoying your heated cabin once again.

Be sure you post up your car's year/fuel/engine/mileage, etc., along with as much supporting data, such as exact trouble codes, symptoms noted, etc., as that will allow members the best opportunity to assist you.

 

If your temp is set to auto then AC will run in winter to remove moisture so windows don't fog 6

 

Just wondering what ended up being the problem? My Q7 started doing the same thing

 

Welcome!

If you learn nothing else from reading this thread or forum, you should firmly understand the Q7 is a complex and highly integrated vehicle; it stores trouble codes inside control modules and it requires you to use a VAGCOM capable scan tool to access these trouble codes, which don't appear as a light on the dashboard display. If you can't read the stored trouble codes on your car, then you usually won't have any basis for making an informed troubleshooting effort or decision. Most issues you may encounter are well known/well documented on this car, but you always begin by doing a full scan for trouble codes on this car...save you a LOT of $$$ and time it will. Once you have trouble codes from a scan, then you can reference against your observed symptoms, and look them up online specific to this car, which will lead you directly to archival threads, such as this one, but on a global scale.

 

I have my Q7 in the shop I was only asking because my will blow the fuse the moment it’s powered up and the scanner can’t communicate because of the blown fuse.

 

This car requires use of a VAGCOM type of scan tool; that just means it is compatible with VW Automotive coding. A standard OBDII scan tool is only able to see the MIL/CEL codes that pop on dash display, but can't read this car's internal modules and trouble codes they have stored, etc.

Listing the details and providing context around your specific car and it's problem(s) is everything when asking for help online; if the scan tool can't read anything at all when connected...i.e. it fails to read the car, then you've got some other issue(s) than what is discussed in this thread, and I'd start by verifying the scan tool is compatible (VAGCOM) with all VW/Audi/Porsche, etc.

Fuses protect circuits and relays toggle power on/off to circuits. Relays can get stuck open/closed, HVAC blower motors go out on this car, an the motor has a variable resistor to control the fan speed...which can go bad over time, etc. We just have zero information about your actual car to be able to assist you further.

Here's a reference that may come in handy on electrical gremlins: https://fuseandrelay.com/audi/q7.html

 

I would really appreciate an update on the fix for this one. I own a 2011 Audi Q7 that is doing the same thing, and I have been trouble shooting it for the past 4 days. I have been able to get my car's HVAC control module to stay on for almost 40 minutes now...but just had the fuse blow again. Here is everything I have done to help you out:

1) Place a space heater inside the car, pop open the sunroof, and with a mini USB fan on inside the car to circulate the air, let it run...mine is going on 4 days. Goal is to remove as MUCH moisture and humidity from my car as I can. I had A LOT of humidity inside the vehicle, especially under the dash board.

2) After getting it to start working long enough to run Ross-Tech, I ran the trouble codes, and had a HUGE list of them...alot of them seemed different from the HVAC issue.

3) Found the earth ground strap under the passenger side of the vehicle. Mounts from the Motor mount to the chassis...mine looked melted, so I made two new straps. One to replace the OEM and One to attach to the Negative point under the vehicle (for jump starts) to the engine. This removed almost 40% of the intermittent issues I was having for codes, and now ALL the codes I have are for the HVAC control unit only.

4) I removed the HVAC Controls from the dash board, took them apart, cleaned the interior of them with a paint brush and electronic cleaner, and installed it back into the vehicle.

5) I cleaned my A/C drain hose (suggested by a different user on a different forum), as they thought it could be plugged...mine was clean.

6) They think it could deal with J126 Relay, which is the fresh air relay, that controls the fan in the vehicle. So I disconnected the fan (unplugged it, under passenger side footwell), and just turned the car onto the ACC option, engine not running. Last night I was able to have the HVAC system stay on for almost 30 mins, before I was satisfied. I then plugged then fan back in, and did the same thing...just battery power no motor. I was trying to eliminate the possibility of the alternator causing the issue.

7) This morning, I unplugged the fan, started the car, and sat in the car with the HVAC stayed on the WHOLE time (20+ mins). Turned the car off, plugged the fan back in, started the car, and left it in the auto setting. Everything worked JUST fine, UNTIL I changed the temperature on the HVAC system. As soon as I turned the dial to over 75 degs, the fuse popped.

My plan now: Unplug the fan again, replace the fuse, and see if I can change the temp on the HVAC with just battery power first. If that works, then with the Car started, and if that works, then I will plug the fan back in and see what happens, with the HVAC set at a higher setting than I had it before.

Here is a link to my other thread with my Ross Tech data so you can see what my codes I pulled. I also attached the Ross-tech data as well.

Ross-Tech - Mystery Fuse Popping on HVAC Control Unit

I would REALLY appreciate any feedback as well, or an update on what your mechanic thinks is the issue or if someone else knows the problem, that would be awesome! Don't really want to part ways with our Q7...but it is the next option at this point, as I am not willing to send it into a mechanic to have them chase an electrical gremlin.

 

The problem was resolved!!! I wanted to wait a couple of days before I stated it was fixed.

It was the J126 relay that was the culprit. I pulled it from behind the glove box, took it apart and cleaned the insides with a paint brush and electronic cleaner, as well as the outer housing. As I was putting it back together, I saw discoloration where the main 6 pin plug goes that looked like water had been there. I am pretty sure the condensation had worked its way under the plug and was causing the short.

When you google search, J126 on an Audi Q7, I only found images showing a blue top controller....its not blue, but black. And it's located RIGHT behind the glovebox above the blower fan. Attached is an image of what it looked like. It comes apart very easily, to clean inside. It is held in by 1/4" bolt heads on either side, and I never saw a gasket. Mine was pretty dirty from 195k miles worth of use...and now still going strong.

J126 relay appearance behind the insulation batting.

What it looks like torn apart and cleaned.