While on warranty, our '96 850 began to produce heat through both side vents, no matter how the air mix is set. The dealer made a valiant effort to fix it, but eventually gave up and called in VOLVO. The Volvo rep. didn't know what was wrong, but drove another '96 850 and declared they all do that. Volvo of North America said that was it, just run the AC when you get the hot air blowing on you! Now, about two years later, the situation has worsened. We can't get heat from the middle vents in the cold weather; it blows ice cold. Any suggestions or fixes wellcome.