Got A Ques About Fan Operation

[94cobraslow]

My 94 been running harm but not over heating! start with whats new on the coolant side it was a sve 3core radiator, new water pump, fordmotorchaft t-stat and hose and both coolant sensors! But here where im stumped the fan work with the ac on car dosent run harm, sec self testkoeo fans turn low and high speed but if the cars is setting there running the fans will not turn on what could that be?

 

[94cobraslow]

And the reason there all new parts is radiator and water pump had a small leak! I was thinking the temp switch that I got is bad or my temp gauge on the car lies!

 

[a91what]

If the fans kick on in both low and high speed from the koeo test, check the ect sensor (engine coolant temp) this is the one that tells the ecu how hot the car is running.
To test this check voltage on the ect with the koeo, with the car cold you should see 2.6ish volts at 90*. At operating temp the voltage should be much lower .6ish or so.

Test this first.

You can search for the surging idle checklist put together on this site, amazing info there. It will have the voltage list for Temps (resistance too) for the ect sensor. It will be within the first two posts.

 

[a91what]

Help me create the "Surging Idle Checklist" | Mustang Forums at StangNet

 

[94cobraslow]

Thats some great info!

 

[94cobraslow]

Haven't got a chance to check the sensor, forgot my voltmeter! But if u unplug the ect sensor when the car run and the fan turn on would that eliminate a pcm problem?

 

[a91what]

The chances of the pcm just up and quiting are slim to none. IMO just replace the sensor or test it. The pcm is doing what it is supposed too based on the info it gets from the sensors, if it can't see the right temp how is it supposed to know to turn the fans on.

 

[94cobraslow]

got a chance to play with it for a min. sensor ohms out 39.4...... test the connector unplug for the sensor koeo 4.61v....... testing from the wires on the connector koeo (pinning the wires) 2.98v think its a bad ect sensor!! band-new sensor from oreillys. what do u think?

 

[a91what]

At what temp was the engine..... the voltage will vary depending on the sensor temp. Use the chart in the checklist I posted it's halfway down the first post.

 

[a91what]

The sensor is fed 5v from the ecu the return voltage tells the ecu what temp the engine is.

 

[94cobraslow]

car hasnt moved in 2 day so im going to say it cold and temp out side is 70deg

 

[a91what]

It a pears to be reading low temp correctly, now warm up the car and retake the reading.

 

[94cobraslow]

ok with the car at normal temp or gauge showing normal temp reading where .521v and sensor ohms out at 2.73..... also let the car run and fan kicked on at the top of the A on the gauge

 

[94cobraslow]

well maybe the gauge is off!!!!! have a auto-meter coming in today so ill know for sure, but from the spec the sensor in range

 

[a91what]

That is normal gauge is off. Good luck!

 

[94cobraslow]

Thanks for the help

 

[94cobraslow]

ok to be continued!!!! got the new temp gauge in and well!!! the fans are coming on at 220 to230 and shutoff at 200. so that same high need some more ideas?
i know the fan works and ect sensor been tested it works and koeo self test fan come on low/high so im guessing the ccrm good because of the koeo self test!this is got me stumped unless i have a pcm or ccrm problem

 

[a91what]

No that's normal

 

[94cobraslow]

ok well i guess i need a fan controller want it to stat around 180 to200! so what is to hot then?

 

[stykthyn]

You replaced major parts of the cooling system. Make sure you have all the air out. Air pockets allow the coolant to boil and overheat. Raise the front of the car on jackstands, remove the radiator cap and let the car warm up. As the thermostat opens the air will run to the highest point which should now be the rad cap.