I have a 97 accord 2.2 lx manual trans non vtech. My cooling fans are not coming on causing the car to overheat at idle. When the ac is turned on the cooling fans do engage. I have checked both fuses and the relay in the fuse box under the hood. i have also replaced the ECT switch that is located by the thermostat. When I jumper out the ECT switch connecter the fans do engage.

 

So you replaced the temperature switch that is on the thermostat housing that has a green plastic electrical connector? Where did you get the switch from? Do you have a volt meter?

 

Yes i replaced the sensor by the thermostat that has a green connector. The new ECT was purchased at Oreillys auto. I do have a volt meter.

 

When the car is starting to overheat, check the continuity between the two pins of the new sensor. They should be a closed circuit by the time the needle gets to the half way mark on the gauge scale.

Resistance test will work too. Infinite resistance when cold, ~0 resistance when coolant gets to around 200 F.

 

Check and bleed the coolant as well. If the coolant has air trapped in it then it will not get the switch "hot enough" (~194*) to close the switch.

And this was the green switch where the lower hose connects....correct?

 

yes it is the green switch that connects to the lower hose on the thermostat housing. I have bleed the system and checked for leeks. I have also returned the switch and tried another brand. the switch does not change state till the gauge is 3/4 up. i have also replaced the thermostat. The lower hose and housing get very hot seeming like the coolant is flowing but it still overheats at idle.

 

so you have checked to see if the fans are running when it starts to over heat(past middle mark)?

both fans turn on with ac?

 

Do both hoses get to the same temperature?

 

both hoses feel relatively the same. The outlet hose is a little hotter. Both fans do turn on with the ac and when the fans engage when the temp is about 3/4 up.

 

When the gauge in the car is over the half way mark, test the resistance across the pins of the sensor you replaced. Let us know if you get an infinite reading, or something very close to zero ohms.