I can't help with the answer, but have the same problem. Summer is not a problem - when I move my heater to cool, the theromostat starts working again, fans go off, life is good. Does not make sense to me. Got my computer read, po 128 and 140. Have read it might be an O2 sensor and that is a quick, cheap replacement, so I'm going to start there next week. I've only put this off 2 years now. If you found anything else, let me know.
Friday, January 4th, 2008 AT 9:14 PM