1996 V6 cooling fan problems

SteveG94GT

Member
Aug 23, 2016
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Hey guys, Have a 1996 V6 that is giving me problems. The radiator cooling fan works and will come on when AC is turned on. It will not, or has not, come on when engine temps need it to. I say has not because I am not sure when it is supposed to. What drew my attention was during its first drive after many months, the gauge seemed to reach operating temp and read steady, then started to climb past the middle of the "normal" range. I would think the fan would, or should have kicked on by that point. I believe the operating temp for this car is 190F to 200F.
After a little research, I thought it might be the Low speed fan relay in the CCRM. I bought a used one, but got the same result. I did test both relays and they work.
I verified the operation of the coolant temp sensor, which does change resistance with temp changes. Also, the fan works with the sensor unplugged, but stops with the sensor plugged in. With the sensor unplugged and the fan running, the engine maintained about 145F, which doesn't even open the thermostat (190F).
I am looking for a schematic that includes the Coolant Temp Sensor so I can figure out where in the system it is. Or is there another test I can run? Is there a way to test the signal from the CTS to the fan or CCRM? Where does the turn on fan signal originate and where does it go on its way to the fan?
If I can't figure this out, is there any issues of me running the car at 145F?

Thanks for any help,

Steve
 
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wmburns

SN Certified Technician
Aug 14, 2009
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A couple of things. Yes the motor running at 145F WILL cause problems.

The 1996 model year V6 Mustang uses a SINGLE speed cooling fan.

Are you aware that IF there's air trapped inside the motor that the air will tend to collect at the ECT sensor (engine coolant temperature)? Further that with air in contact with the ECT this will make the sensor read LOW? In addition the air will block the flow of coolant. So this creates a situation where the dash temperature gauge can read low while the motor is actually running hot.

Here's some information on the correct procedure to bleed the air from the V6. The V6 is bad about trapping air inside the coolant jacket and this procedure should be followed EXACTLY.

V6 coolant refilling procedure:
https://www.allfordmustangs.com/forums/v6-tech/299481-1998-mustang-irregular-rpms-showing-hot.html#2604913

Finally if you are truly interested in correctly trouble shooting the cooling fan circuit here's some information on an affordable ODB2 scanner that will change the entire process. This ODB2 scanner is capable of two way communications with the PCM. There's a method to "command" the PCM to turn on the cooling fan. This gives an easy straight forward method to confirm IF the PCM does indeed have control over the cooling fan. Further this gives an easy way to find out what the PCM "thinks" the ECT value is.

Using an ODB2 scanner will change the way that one goes about "fixing" cars from that point forward.

ForScan ODB2 scanner w ELM327 USB
https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/
 
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SteveG94GT

Member
Aug 23, 2016
18
5
13
49
Mr. Burns

Thanks for your reply. I did not realize about the possibility of trapping air at the..ECT. Is that the Coolant Temp Sensor? I will do the refill procedure.
And thanks for the scanner idea. My other one is a 94 and never realized that this one, 96, could use the ODB2. I will get one this weekend.

Thanks again!