Damn cooling fan again

pipecraze

Registered User
I think my coolant temp sensor isn't working.


Here's what I have:

-Both fans come on during KOEO test.

-When engine is running the fan comes on when I pull the temp sensor connector. Fan turns off when plugged back in.

-If I turn the ac or defroster on the fan will not come on.

-If I let the car run hot the fan will not turn on.



I'm on my second brand new temp sensor from Autozone! How can I check the sensor to make sure it's good.
 
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Not sure, but I have done away with that years ago. Either cut wire 14 from the IRCM/CCRM or wire it up to a switch w/ a relay.

If you put in a new temp sensor and it works, then you know the sensor is bad. Try a different supplier for the sensor, maybe Advance Auto, NAPA, or somewhere else as long as they aren't the same brand sensor. Does MOTORCRAFT sell these anymore?
 
I bought another temp sensor from advance auto. When the car cools down I will be able to see if my problem is fixed....I certainly hope it is! I've been having cooling issues for over a year with this friggin car!
 
I installed the thrid new engine coolant sensor today and still the fan still won't come on when I put the ac or defrost on. Whats the deal with this POS!

Both the low speed and high speed came on for the KOEO test so I assume the fan motor is good. IRCM is about a year old.
 
First off, does your a/c work? If it doesn't the fans are not going to come on.

Second, as an FYI.. the low speed will not kick on till your car hits 220F, and the front fan will not come on until you hit 228F. Is your car getting that hot?
 
First off, does your a/c work? If it doesn't the fans are not going to come on.

Second, as an FYI.. the low speed will not kick on till your car hits 220F, and the front fan will not come on until you hit 228F. Is your car getting that hot?


The a/c does not blow cold. The fan had come on though when set to defrost.

I'm quite sure the temp had exceeded 220 and the fan did not come on. Today the idiot gage read past the M and set off the check gages light....no fan!

I'm trying to fix this without cutting wire 14 although I may do that to save my engine in the meantime!
 
If the IRCM was bad the fan would not run during a KOEO test.

Does your AC Clutch engage when you turn on the AC? If the freon is too low the clutch is blocked and the fan will not come on.

The ECT is a thermistor that has a resistance value that drops as temp goes up. You could take a resistance reading across it. +32 deg F should be close to 30 K ohms of resistance. I would have to do some temperature conversions for other temps but they range from -20 deg C = 271 K Ohms to +120 deg C being 1.2 K ohms.
 
Well the fan is actually coming on after the car get's hot. It just seems like it's geting very hot before kicking on.

One question...will the fan come on when switching the defroster on even if the a/c is bad???
 
First off, does your a/c work? If it doesn't the fans are not going to come on.

Second, as an FYI.. the low speed will not kick on till your car hits 220F, and the front fan will not come on until you hit 228F. Is your car getting that hot?

That's starange because my ac doesn't work and my fans work?
 
That's starange because my ac doesn't work and my fans work?

A method of testing the low speed fan is to turn on your a/c. If the a/c is functioning properly, then the low speed fan will kick on, providing the IRCM is working properly. Even if the a/c doesn't work, the fans will come on at the set temperatures it needs to.
 
That's starange because my ac doesn't work and my fans work?



Does your fan come on when you switch on your a/c? Even with my a/c not blowing cold the fan used to kick on when I turned the a/c or defroster on. Not anymore. I am tempted to get the a/c blowing cold but we're going into winter here. Just seems a little strange to me.

At this point I'd just like to fully understand why the fan isn't coming on when the switch is set to either defrost of a/c. I don't know much about the a/c system. If in fact eveyone says its the non-operational a/c then I will charge the system and report back the results.

Anyone else have any input. Thanks for eveyones replies so far...everyone has been very helpful!
 
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How do I tell if it is cycling. I don't believe it is though. I don't know much about A/C.
With the engine running, watch the compressor when you turn on the A/C or defrost. If the center grabs and spins, then its engaged. If it doesn't engage, then the fan probably won't run. If the clutch engages and the fan STILL doesn't run, turn the A?C off.. as it will soon build up too much pressure.

If the fan runs and the clutch engages, then watch it for a minute or so.. it should disengage for a couple of seconds and then engage again. This is what is referred to as cycling. It is supposed to operate in that way.
 
I wonder if the gauge isn't wrong for some reason, because everything suggests that the ECM recognizes changes to reported engine temp, and can control the fan. I'd try to find a way to verify actual temp with a thermometer, probably use one of those infrared thermometers, or grab a multimeter and backprobe the ECT colored wire at the connector and see what the ECT sensor is reporting. Although I'd actually like to know both.

edit: also, clear codes, since it'll have one set for the ECT circuit you unplugged, and then retest
 
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