Heated Seats: Slow to Warm Up?

Hello, I'm having a problem with the driver's seat heating in my Audi. Unlike the passenger side, which immediately provides warmth, it takes about 10-15 minutes for the driver's seat to warm up slightly. I read a similar post about a relay with poor contact surfaces...
Can anyone tell me where I can find the relay? ...or even provide a wiring diagram? I'm at my wit's end with my Etzold device; there's no wiring diagram available for it.

Sure, here's the translation:

'Thank you in advance.'
René.

Hi Rene_S,

'I don't think you need a wiring diagram for this. Just try swapping the seat heater controls between the driver's and passenger's sides. If the problem then moves to the passenger side, next compare the resistance values of the heating elements in both seats.'

Hi Marco, Thanks for the quick reply. I'll test the regulator tomorrow.

However, I can't imagine that I have defective heating mats. They are working, but I suspect they are being intermittently/randomly supplied with voltage. ...but as I said, presumably. That's why I'm looking for the wiring diagram.

René.

Hi Marco, Thanks for the quick reply. I'll test the regulator tomorrow.

However, I can't imagine that I have defective heating mats. They are working, but I suspect they are being intermittently/randomly supplied with voltage. ...but as I said, presumably. That's why I'm looking for the wiring diagram.

René.

Hello Rene,

'I had this problem with my Passat 94. Usually, the resistors within the heating elements are corroded and have a strong electrical contact, which causes the heating element to shut off prematurely (you can hear a click under the seat). To avoid having to replace the heating elements, you can also increase the resistance. Simply solder a resistor before the potentiometer of the seat heater (the adjustment knob), and it should work again.'


Best regards, Manuel.

Hello Manuel,

If you're referring to a clicking sound, should I also look for the relay there? I'll try to listen for it later. I should be able to find the relay under the seat, which is where I've been looking for its location all along.
Thank you.

Hi,

"A relay located under the seat would surprise me. Usually, they are integrated into the switch/control unit housing along with the electronics, and that's where you would normally hear a click. You could test that with the working side to see if that's the case."

Best regards,

Jan.

Hallo, ich habe die beiden Regler getauscht. Keine Besserung. Die Kontakte der beiden Anschlußstecker habe ich miteinander verglichen. Unterschiede konnte ich keine feststellen. Klicken habe ich keines gehört, jedoch ein leises summen irgendwo unterhalb der Konsole. Das Summen war unabhängig von der Reglereinstellung. Klimaanlage off... (This likely refers to a specific system or device, and without more context, a direct translation is difficult. It could be something like 'imaanlage: power off' or 'imaanlage: system offline.')


René.

Hello Rene_S,

Since the regulators are not the issue, the next step would be to examine the heating mats themselves. One possibility is to measure/compare the current draw of the mats using an ammeter. Before doing so, make sure to disable the side airbags in the seats using the appropriate dummy plugs, if they are present.

Hi,

If you feed the current for the measurement through the connections on the switches, the airbag system is not involved. However, you then need to trace the cables or have a wiring diagram to determine which wires are connected to the ammeter so you can feed current into them.

Best regards,

Jan.

Hi Jan,

'Of course, that's also an option, but I always prefer the 'direct route'.'

Hello.
Today, I compared the resistances of the two connectors for the control units.
Pin 3, according to statements from another thread, is the temperature sensor located in the seat.
26 Ohms (slow side) to 21 Ohms (working side), measured at 2°C inside, while I was sitting on the 21 Ohm side.
Pin2, the seat heating pad(?) : 19 ohms on the defective side, compared to 2.2 ohms on the functioning seat cushion.

I couldn't measure any differences in the other contact points.

René.

Pin2, the heating pad in the seat(?) : 19 ohms on the defective side, compared to 2.2 ohms on the functioning seat cushion.


Using the formula I = U/R, we find that 0.63 amperes are flowing on the faulty side (12V / 19 ohms), while 5.45 amperes are flowing on the working side.

The power on the faulty side is P = U * I = U * U/R = 144/R = 7.5 Watts, while on the working side it is 144/2.2 = 65 Watts.

With only 7.5 watts, the seat is unlikely to get very warm.

Somewhere, the resistance is too high. If you're unlucky, the heating element is broken; if you're lucky, there's just a bad connection somewhere.

Ideally, you should measure the resistance as close as possible to the heating pad. If the reading is significantly higher than 2.2 ohms, the heating pad is faulty. If the reading is okay, you need to inspect the wiring all the way to the switch and the ground connection, as the problem likely lies there.

Regards,
Private.

Hello,
Unfortunately, I measured the same resistance directly at the connector under the seat.

I would like to thank everyone who helped me along the way.

René.

Hello,
Unfortunately, I measured the same resistance directly at the connector under the seat.

I would like to thank everyone who helped me along the way.

René.

Hi,

I'm having the exact same problem; I also suspect a faulty sensor pad. Could you let me know how much it costs and how much effort is involved in replacing it, if you've already done it?


I can roughly measure similar values (default and OK) in my car as well.