I've got a York Affinity 9.M furnace that was installed (brand new) in my Portland, OR home 3.5 years ago. During three of the four winters I've had it, it has stopped working at least once with the same problem: It flashes three red lights, which is code for "pressure switch stuck open."
The original installers have been good about coming out here and replacing the pressure switch for free each time, and once they replace the pressure switch, it works fine (until the next time). It hasn't cost me a dime, but it's extremely inconvenient, and it only seems to happen when we're having the coldest and/or windiest weather of the year. I've probably gone through five or six pressure switches in four years.
I was told that this is due to a defective pressure switch that York uses in their newer furnaces, and that there's nothing to be done about this except replace it when it goes bad. I find that hard to believe (and harder to believe that someone hasn't filed a class-action lawsuit against them by now if it is true). Can any pros out there lend some insight?