I just bought my first volvo last week and was disappointed that both heated seats didn't work. Well, after much research I decided to take a look under the seats to see what I could find. As soon as I looked under there I noticed two wires (a red and a red/white wire) going up into the bottom of the seat cushion. As I looked closer I saw what was wrong, the red/white wire had broken off. WHEW... I had some hope. I reached up in the seat where the wires were going and grabbed hold of a plasic disc shaped thing that the wires were plugged into and pulled it out of the seat. I realized this plastic disc shaped thing with a dime size metal disc was the thermostat. Well I simply crimped a new connector end on the red/white wire and plugged it back into the thermostat. Then I took the whole thing and pushed it back up into the bottom of the seat cushion. I then started the car and turned on the heated seat switch. To my amazement the seats started to heat up. Keep a long story short, I checked the passenger side seat and it was the same thing, the red/white wire had worn off and was hanging on by a thread. I fixed the wire and then that seat started working again. Well I thought I would share this with you incase you are looking for the same info I was looking for the past couple days. Just reach up in the seat where the circle hole is and pull out the whole thing with the wires still connected and very carefully check the wires to make sure they are still connected good. From what i have read, 90% of the time this is all that is wrong with it.