My vehicle runs great and only has two - three problems. The first one I am attempting to remedy is my cooling / radiator fan not turning on when the engine reaches operating temperature and above. Let me explain:

The overheating occurs when the vehicle idles or is in slow stop and go traffic. From what I've read your radiator fan should turn on during these times to assist the radiator in cooling the engine. Mine does not. Troubleshooting thus far:

If I turn the A/C on manually both the condensor fan and the radiator fan turn on. No squealing, noises or anything. So I assume both motors are fine. The radiator fan does turn on by itselfafter the vehicle isstopped, turned off, and keys pulled from the ignition. (Therelay that controls thisis the one behind the glove box correct? ) I purchased a multimeter so I could test the relays, fuses, and sensors. I have tested the radiator fan relay behind the glove box; all wires except black to ground register 12v. I pulled the cooling fan fuse from underneath the steering column and it looks fine. I pulled the cooling fan fuse from the underhood fuse box and it has no burn marks and seems fine. ( This fuse states it needs the 12v to close the circuit to the other two pins, does this fuse control both the condensor and radiator fan? Also will 12v go to the fuse if I just turn the ignition to on? Or do I have to get it there from the battery via a wire?) After driving the vehicle for some time, and knowing the thermostat is open (Both upper and lower radiator hoses are hot to the touch ) I "jumped" the connector that attaches to the engine coolant sensor which is located at the thermostat housing with a paper clip; both fans came on.

- With these results my conclusion is: My fuses, relays, electrical wiring, and fans seem okay. The coolant sensor at the thermostat housing is faulty?

*I have replaced my thermostat at the begining of this endeavor so its new and from the looks of it working correctly. My old was fine so I'm just out 15.00.

Another question: While reading my Haynes manual it stated to "Test the continuity" of my sensors. I bought myself a multimeter. Switchedthrough theentireohms scale available on the multimeter, and I don't know what to do from here. It states there should be no continuity when cold and is should change when engine is at operating temperature and the thermostat opens? I dont' understand how to test the sensor. If someone could explain to me and give me an idea of what type of readingsI shouldsee. Let me explain what I've tried so far:

I unplug the sensor, ( The vehicle is off at this time ) Set the multimeter to 20 ohms scale,I touch the nut part of the sensor with my red lead and touch something else metal on the vehicle. The ohms readings jump up and go down from 100to about .2 - .6 and stay at the lower end. *Note: If I touch the black lead to one of the A/C condensor lines the ones where you can refill your A/C lines "H" and "L" I get much higher readings 17 ohms for example* I tried this with both the ECT and the condensor sensors which is at the upper radiator hose. Both get the same readings. Second: I touch the red lead to one side of the nut sensor and the black to the other side still same sporadic readings and they settle down the the .2-.6 range. That is either cold or when engine is hot.

Am I testing these correctly? Is my guess that the ECT is the faulty part in question? This is my first time using a multimeter or working on a car, I'm starting to like it so I want to understand how to use and read my new tools.

I just would like to bounce my ideas and findings amongst everyone before I begin buying new parts. I don't want to end up with a shoe box full of new parts, or old and still good ones.

Thank you in advance for taking the time to read my post and offer any advice or opinions.

 

You should put your year and model in the signature.

Basically the temperature sensor A is a switch that turns ON at a certain temperature. If you just bought your multi-meter, it might have a continuity setting where the meter beeps for a closed circuit and doesn't beep for an open circuit. Look in the manual that came with it.

You can read it by resistance. When the engine is cool, the resistance should be infinity. Using the ohm setting on the meter, the reading should be the same as having the leads touching nothing.

When the engine is hot, the resistance should be some number that is on the scale. You might have to switch the scale to get a reading. You can also try the test on temp sensor b (it turns on the fans when the car is off) to test a working sensor.

Remember to test temperature sensor A. The engine coolant temperature sensor is a different sensor and changes resistance continuously as the temperature changes. The temp sensor A is more like a light switch (on or off).

 

Sorry, I thought I put my vehicle specs in the signature. As follows:

1995 Accord Coupe LX, 2.2L AT, Engine F22B2
Mileage: 203,000

My multimeter does have a beep. It says it will beep if the ohms are below 30. The readings I have available are: 200, 2k, 200k, 200m. So to test the sensor; I ground the black wire to a metal object, and then touch the sensor nut with the red to get a reading? Or do both leads of the multimeter touch the sensor? Then switch through the available reading scales when the motor is hot and the thermostat open to get a reading? Would both sensor A and B have approximately the same reading on the ohm scale when hot? If no reading is found on the sensor when hot then the sensor would be bad?

Sensor A is at the thermostat housing near the lower radiator hose,
Sensor B is at the point where the upper radiator hose connectings to the motor? ( I'll have to check my book it has it written alongside a picture )
There are two more on the side but it they are a bit hard to reach. One smaller then the other 3.

With the information given on my vehicle and the way its acting, am I making a good assumption that the fault in the circuit is most likely sensor A?

 

I think that you are on the right track.

You test the sensor by putting the meter on both leads of the sensor.

 

I don't understand when you say " by putting the meter on both leads of the sensor " What are the leads of the sensor? Are those the two prongs where I plug the switch in?

 

You touch the red meter probe to one of the pins on the sensor, and you touch the black meter probe on the other pin of the sensor.

 

This is the replacement part I'm going to buy. Is this the correct replacement for sensor A?

http://cgi.ebay.com/ebaymotors/ws/eB...m=180267878532

 

No, this is coolant sensor. You need thermoswitch A. Following is one very similar to yours. I couldn't find one on ebay, but didn't look too hard. You may have to go OEM. Price is not too bad last I checked.

good luck

http://cgi.ebay.com/ebaymotors/Water...mZ380058977238

 

Just dropping back in to write up my resolution. I ended up buying a radiator fan switch from autozone. I switched out the switches and both fans turn on. It was a faulty water temperature switch. Thanks to everyone and the forum for assisting me, these posts hold great answers to questions and troubleshooting. Good luck to everyone on their car to do lists!

 

Thanks for the followup. It's good to know if advice works, or not.

regards