Ok so here is my predicament. Just did my JDM H22 swap in my 97 Accord LX. Problem is misc. heating up. A few examples would be driving on the highway at about 80/85 MPH the gauge was sitting at 1/2 when usually the gauge never budged above above a lil over a 1/4. When I started hauling *** on the highway it raised even more above 1/2 so I slowed it way down and it eventually went down to 1/2 which is still high!
So to try and fix the problem I changed out the thermostat with a Autozone one and it still did it so I threw in the stock one again. So then I thought that the radiator needed a coolant flush so I got one done and filled it with 50/50 mix again. Everything was fine until it did it again. This time was around town normal driving with the A/C on(And Yes BOTH fans were on) So I turned the A/C off and the problem went away. So to try and show my buddy who owns a shop the problem I beat the crap out of it for like 10 minutes straight and no heating issues. This has boggled my mind for weeks now.
Also to add to it.......both fans work but you know when you turn off your car if the temp is to high the fans will kick on by themselves and run for a while until the correct temp. well ever since the swap they have never come on, even if the temperature is above half, I have to sit there with the key on the ACC position until the fans stop by themselves when the car was to hot. So in conclusion Both fans work, thermostat was fine because I swapped it with a Autozone one and it did the same thing and the water pump seems to have good pressure and it doesnt raise temp at a light even if I sat there for 5+ minutes.
Also for a better description, yesterday it was raining out so I was using the A/C and it was muggier than hell outside(I live in FL.) and the temperature never even budged. This is the weirdest problem I have ever had. The ONLY thing I can think of is the sensor that we swapped over from my F22 to my H22 that controls the fans/thermostat. Any help would be DEEPLY appreciated. Thanks......sorry so long.

 

you may have a cooling problem, or a sensor problem. If it isn't consistent you may want to check the coolant temperature sensor.

It could be giving a bad reading to the gauge. Are you positive the car is hot and its not just the gauge saying its hot?

I can'y say its definetly your problem, but it just popped in my head after reading your post

 

I am not sure if the engine is actually getting hotter or if the gauge is just reading like that but, the sensor is off my F-series and it worked fine on that motor. Never moved the needle past where it should have been.