Overheating Accord1997 Automatic
 

I experience having the engine overheating. The temp gauge just goes up but the radiator fan does not turn on even when the temp is at half the gauge. But both the radiator and auxilliary fans turn on when the aircon is turned on. Supposedly, even if the aircon is not turned on, the radiator fan should turn on when the temp gauge reaches half way. But in my case, it doesn't and it just turns on with the auxilliary fan when the aircon is turned on. What could be the problem? What signals the radiator fan to turn on? Is there a switch I need to look at for this one?

In addition, I also observed that the upper radiator hose is so hot while the lower radiator hose is just warm. Is there a possibility that the water is not circulating? Could it be a thermostat problem? The level of coolant is just ok.

I also observed that when I turn off the engine because the temp is already high and overheating, both the radiator fan and auxilliary fan turn on for minutes as if trying to cool down the engine.

Did you check the coolant level by removing the radiator cap when the engine is cool? Make sure that there are no leaks.

There are a couple of possibilities that may be causing the overheating. First I would replace the thermostat with one from the dealership (~$15).

The radiator may be clogged. When you drain the coolant to replace the thermostat, run some coolant system flush through the car to clean out any scale that may have built up over time.

I wouldn't jump to replace the water pump unless your timing belt is due for a change or if it making a squealing noise.

There are two temperature sensors that will turn on the fans. Sensor A controls the fans when the car is running. Sensor B controls the fans when the car is turned off. If the fans turn on when the car is running, then sensor A is ok. There are some resistance tests that you can do on that sensor. Get a 94 shop manual from the links in the online manuals thread in the DIY section.

Thanks PAhonda.

I checked on the level of the coolant and there seem to have decreased level. I am not sure if this is because of leak since there are no drips anywhere under so I suspect that this is just due to some evaporation for the long time my car has not been used. Would you think this is so?

Would you be familiar where the sensor A is? Even if the temp gauge reaches the half way mark, the radiator fan does not turn on. But when I turn on the A/C, both the radiator fan and aircon (auxilliary) fan turn on.

Thanks for your further advice.

Sensor A is on the thermostat housing. The circuit should be open when the engine is cool and should read closed when the engine is warm (definitely before the halfway mark on the coolant temperature gauge).

If you go to the Online Manuals thread the spoon honda link has a 94 shop manual that will help out a lot.

http://techauto.te.funpic.org/mainrelaydefine.php

once you open the link,, click on the troubleshoot tab......scroll all the way to the top,, on the left upper corner ( repair guide ) click on the overheating tab,,, it should help you understand and diagnose..