01 accord. The temp gauge is stuck at middle. Not cold, not hot. What might issue be? Bad cluster? Or temp sender?

 

Is it still stuck in the middle when you turn off the car (key out)?

 

Key off, and removed, it drops to bottom. Like below cold

 

What make you think that it is stuck at the middle? Define your middle. Have a picture? Has it always been that way? any work done to the vehicle recently?

 

If you start the engine cold, and it immediately jumps to the middle, that's not realistic for the actual temperature to behave like that. That's one way to answer Celicool's question.

In 2001, I think the temperature sensors are wired into the PCM, not directly to the gauge like older Accords. Then the PCM drives the gauge cluster. So it could still be a bad sensor, or bad wiring anywhere along that signal path.

 

Cold engine.

 

Ok. Now you need to figure out where in the circuit you are having problems.

The temperature sensor send the coolant temperature to the engine computer (PCM). The PCM uses that coolant temperature for air/fuel ratio and also sends the signal to the gauge.

Do you have access to a scan tool that can read live sensor data?

 

pcm may think motor is always warm? I can drive for awhile and than stop and idle and cooling fans will kick on for 10 sec or so. If I turn on AC, the fans start immediately.

 

I agree with others that your instrument cluster is probably fine. I don't know if there is a way to test for good/bad temperature sensor, but you can probably google that information. Another cheap option to try is pick some up at your local junkyard--there should be quite of few of 2001 accord around.

 

Next question; define "cold engine". On a very hot summer day, hot as in above the 100°F threshold, I've gotten in my Accord and seen the temperature gauge register above "cold" immediately after a cold start. That said, on cold mornings when the OAT is say -10°F, I may have to drive an easy five or more minutes before the needle lifts of the low point of the gauge.