I have a 1990 Accord LX. In the spring of 2004 I had a new radiator put in with new hoses and cap. I installed a new (170 degree) thermostat myself. That summer (or whenever it is warm) the temperature gauge starts to move up when the AC is on or when the car is full of adults (5) and it has to work hard (AC or no). It never gets to the point of boiling over because I turn on the heat and it comes back down right away. During highway driveing or cold weather it is never a problem. It's also not a prolem in the summer time with just 3 of us in the car and no AC. Both fans work. Finally, when I turn the car off the fan kicks on much more frequently that it used to, even if it has not gotten hot while driving. The thermostat has a bypass of some sort(a hole in the flange with a loose pin in it. Could I have installed that incorretly? Could it be the temp sensor? Thanks for any info you can give me.