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2010 Audi Q5 - Seat heater question

We have a 2010 Audi Q5 and for everyday driving conditions our seat heaters never really reach a hot level. However, I’ve found that the seat heaters can reach bun-toasting levels when certain conditions are met. For example, on the rare occasion that my wife lets me sit in the car while she goes shopping (taking a nap is much preferable than waiting outside a dressing room), I find the front seat heaters can get really hot after restarting the engine. But, this only happens when I shut off the car, stay in the car without opening any of the doors, wait for the “click” noise (~10 minutes after shutting off the car) and then restart the car. I’ve taken the car into the dealer and they indicate that the seat heaters are “working”. Is there any way for the heaters to operate at the “hot” level without having to go shopping?

Cold Buns

Maybe its the way they are suppose to work.You probably find the answer if you read the owner’s manual.

?? You mean the seat only gets hot after I turn on the car, turn it off, sit in it for ~10 minutes and then restart it? I don’t think so. The cars that we test drove before purchasing had hot seats from the get go. Hopefully this isn’t the only response from my question.

Did you recently buy this vehicle, or have you owned it for the past 10 years?
If it is the latter, is this a new problem, or has it always functioned like that?

We are the original owners. Yes, it has always performed like that.

If this took place w/in the first few years that you owned the vehicle, and if the dealership’s actions didn’t satisfy you, then you could have referred your complaint to Audi at the corporate level.

But, after 10 years, I doubt if Audi corporate would now intervene, so I think that your only option would be to take the vehicle to an independent mechanic who specializes in foreign makes.

I was looking for advice on what to fix. That way I can call around to find the best place to have it fixed.

This is a very particular problem, not something most (or any) of us have dealt with. Have you posted this on Audi forums?

How many levels of heat are there, and which level(s) do you use?

6 levels and we always use “6” because there is barely enough heat on “6”.

The heaters use electric current to the resistive heating element in the seat. Increasing current increases the heat given off by the resistor. There is also a thermostat that monitors heat, and when it is tripped, it shuts down the current until the heat is low enough to turn it back on. The switch activates a relay to tell the system how much current to provide. The problem is likely not with the heater elements or thermostats, since they are in both seats. Unplug one of the seat heater wiring harnesses and test the current level when the heater button is pressed. Cycle through all six settings and see if the current changes. If not, there may be a problem with the relay.

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Ok. I will try that. Thank you.

Yup…basically everything that @jtsanders said… The one thing i was trying to fathom was what causes the heat of the elements to be affected by the restart? Since there are green boards of mystery and science in play here it may be an electronic bugaboo.

It would be interesting to know the voltage with the engine running while seats are not hot enough…and then another reading after the restart.

This is an educated guess but…If the alternators output leans toward the higher end of the acceptable scale… maybe the electronics are dumbing down the output on purpose based on too high an input voltage that is only experienced while driving and higher alternator rpm’s. Once it dumbs itself down… it requires a restart to reset and reach bun toasting levels… Not sure if the restart is combined with sitting and not driving / not raising engine rpm / alternator rpm’s ?

I dunno… something like that… To me, this seems to have a flow of logic… Cant hurt to measure the output of the alternator at startup…with rpms added and at idle… Might shed light…on something… somewhere. lol

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This is the best way to begin the diagnosis but it won’t draw any current without the load connected. You either need to connect an ammeter in series with the load or use one of those clamp on ammeters to measure the load current.

If you can’t do these kind of tests yourself, you need to find an automotive electrician- someone that specializes in electrical diagnosis and repair. This would be the fastest and best solution. You may find a competent tech at any dealership or independent mechanic shop but that may be hit or miss. The other thing you need is the specifications for current for at least maximum setting. Then you can verify it’s out putting the right amount and any of the lower settings should just be reduced amount from max.

I don’t think it’s the element itself because it works sometimes, under strange set of conditions. There is also probably an occupant present sensor in the seat bottom that controls whether or not it functions. The one under the drivers seat in my truck was marginal and sometimes, the heat was lacking. If I sat down with authority, sometimes it would work properly :slight_smile: A schematic of the entire circuit will be very helpful in diagnosing the issue…

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I wonder if the system alters the voltage. That’s easy to measure, compared to current.

No wonder the sparkies use breakout boxes at work.

Normally, they just adjust the load because that’s the easiest way to do it. Even so, measuring voltage won’t tell you if the load is compromised. You’ll only get a small part of the picture- the supply side.

Looks like at least a few mfrs use series/parallel load resistors. The switch alters the configuration between the ballast being in series or parallel with the load. Then, if the over temp switch activates, it automatically removes the parallel supply and reverts to low heat.

Boy, do I feel bad for mechanics that have to read and understand these vehicle schematics. Most look like they were generated by mechanical engineers versus an electrical engineer. They look pretty but are often hard to read…