Radiator fan acting crazy!

Nando559

Registered User
My radiator fan stopped working. I swapped out my IRCM and it wouldnt turn on still. I checked to see if the fan was getting power by turning on the ac and checking the connection for the fan. There is power going to the low speed. Next I check to see if both speeds work and they do! For some reason I decide to remove the small wire that is grounded from the ground wire on the battery to the body of the car. Normally ive seen the small wire from the negative put together with another small wire but my car has them separated. If I ground both wires the car starts but the fan will not turn on..if I remove the wire that comes from the ground off the battery, the fan turns on as soon as I turn the key but my car wont start! Anyone know what is going on with my fan and the mystery grounded wires?:confused:
 
Maybe

Did you check the temp sensor on the passenger front top of the intake manifold? I know that that is what turns the fan on at a certain temp.
 
Sounds like maybe the ignition switch (down on the right side of the column, under the dash) might be acting up.
 
Ive read that the EEC-IV Module controls the fan also. Where is that located..i have a 1990 THUNDERBIRD SC AUTO.
 
Just want to point out to make sure that you got the temp sensor for the EEC and not the temp sensor for the gauge. I believe there are two separate ones. I know my fan wouldn't turn on at the correct temps after I replaced my IIRC an I needed the temp sensor that sends information to the EEC. Just a thought.
 
Just want to point out to make sure that you got the temp sensor for the EEC and not the temp sensor for the gauge. I believe there are two separate ones. I know my fan wouldn't turn on at the correct temps after I replaced my IIRC an I needed the temp sensor that sends information to the EEC. Just a thought.

Are there two sensors that look alike? I replaced a plastic sensor that is located on the passenger side upfront next to the fuel injector. It was plastic and the replacement they gave me is made out of a type of metal. Did the autoparts store give me the wrong part?
 
You should definitely look into that as I believe they look similar and have similar names. Hopefully someone that knows for sure can chime in. The one I replaced that sends the engine temp info to the EEC was metal and actually touched antifreeze when screwed in. I'm trying to remember where that one was located...I think it was toward the front center of the motor, but don't take my word for it.
 
You should definitely look into that as I believe they look similar and have similar names. Hopefully someone that knows for sure can chime in. The one I replaced that sends the engine temp info to the EEC was metal and actually touched antifreeze when screwed in. I'm trying to remember where that one was located...I think it was toward the front center of the motor, but don't take my word for it.

Are you talking about the one next to the thermostat? It has a small tip that you push a red connector onto?
 
sensor

Are you talking about the one next to the thermostat? It has a small tip that you push a red connector onto?

The one next to the thermostat is the gauge sensor and should only have 1 wire coming off the top of it. The temp Sensor for the EEC and fan is the other one, has a few wires at the top coming off. The one that you replaced sounds to be the correct one.
 
Last edited:
well just to be on the safe side, I replaced both of the sensors. Since that didn't work, is my next step to replace the EEC-IV Module??:confused:
 
When you unplug the coolant sensor does the fan turn on?

Do this while the car is running, it should turn on.

Make sure your cooling system is full and gets pressurized.

Your fan won't turn on until it reaches operating temp, sometimes that can take a second or two. :rolleyes:

Make sure this ground you speak of is connected correctly. I don't think it has anything to do with your fan but try and put it back the way it was. This just takes another variable out of the equation.
 
When you unplug the coolant sensor does the fan turn on?

Do this while the car is running, it should turn on.

Make sure your cooling system is full and gets pressurized.

Your fan won't turn on until it reaches operating temp, sometimes that can take a second or two. :rolleyes:

Make sure this ground you speak of is connected correctly. I don't think it has anything to do with your fan but try and put it back the way it was. This just takes another variable out of the equation.



I unplugged the sensor and the fan did turn on!

How exactly do I get the cooling system pressurized?

the fan does not turn on even when the temp gauge goes pass the "L" and if I keep running the car it'll light up the "check gauges" light.

As for the two wires grounded to the car..I've seen many SC's with it. It goes from the battery to the car, then another wire goes from the grounded spot out towards the radiator. I left it how it was because the car had been working perfect like that.
 
By keeping the cooling system full it'll pressurize itself once it gets to operating temp.

Use a thermal gun or something of the sort and monitor the heat at the thermostat housing. I see my thermal gun reach about 220-230 degrees before my fan comes on. Now, that of course is the temp of the housing and not actually the temp of the coolant. It's just a measure that I go by to know when the fan should be coming on.

Oh, and I thought the gauge said NORM, I don't know where you are getting L from but I'm not in front of one right now and could be wrong.
 
By keeping the cooling system full it'll pressurize itself once it gets to operating temp.

Use a thermal gun or something of the sort and monitor the heat at the thermostat housing. I see my thermal gun reach about 220-230 degrees before my fan comes on. Now, that of course is the temp of the housing and not actually the temp of the coolant. It's just a measure that I go by to know when the fan should be coming on.

Oh, and I thought the gauge said NORM, I don't know where you are getting L from but I'm not in front of one right now and could be wrong.

Ok, I will go out and buy a thermal gun today if possible. I will check my housing when I get it to see what my temperature reads.

My mistake, I just went out to check the gauge. You are correct, I meant to say it goes to the "M". when it barely goes past the "M" my red "check gauges" light comes on and I turn the engine off. Then manually turn the radiator fan on.
 
Just some FYI,
Duffy Floyd
Guest Posts: n/a

The BLACK Box otherwise known as the IRCM

--------------------------------------------------------------------------------

The IRCM (Integrated Relay Control Module) IS a black box mounted in front of the air cleaner box on the passenger side of the engine compartment just forward of the unibody crossmember. Some of its functions are understood and many are not. Lets discuss what is somewhat commonly known.

1) The IRCM contains discrete electrical components to perform electrical control operations for the car. Some of these functions include:

a. It controls the low speed and fast speed radiator fans based on input from the EEC. Once a certain temperatures of engine coolant are obtained it will turn on the fan and control its speed (either slow or fast) based on the operating condition "seen" by the EEC. The EEC gets this temperature input from the ECT Sensor which is located on the passenger side front of the engine at the intake manifold connection of the heater hose. It will also turn on the fan in slow speed if the AC is turned on. (Assuming the AC System is operational. If low on freon the compressor will be "protected" from operating by a low pressure cut-out switch in the AC System thus the fan will not be activated. This is however a good diagnostic tool for determining where the electrical problem you may have resides. If the fan runs it is probably NOT the IRCM)

b. It also controls the ECA Power Relay which provides electrical power to the EEC. This is NOT the power used by the KAM memory function of the EEC but rather the "main" power for the computer.

c. It also "controls" ( based on the AC Switch in the car being turned on AND the above Low Pressure [actually a cycling pressure switch] being closed),the AC Clutch coil which energizes and allows the AC Compressor Clutch to be engaged turning the AC Compressor shaft itself as opposed to just spinning the pulley.

Now to the "good part and hereto know to only a few.........ready????????

d. The IRCM has a 24 pin connector associated with it and the features we have discussed only take up a small portion of the "slots" availalble. In fact ALL of the above functions represent only 17 out of the possible 24 terminations. So what are the rest used for?????? Many pass through connections for various engine control components like 1) the fuel injector current path from the battery to the EEC through the injector themselves 2) Power to the WOT AC Cutoff Relay comes from the IRCM (this drops out the AC Compressor at WOT), 3) there is a termination used to feed Ignition Switch Battery Voltage to the Coil 4) the alternator field flash power from the battery is feed through the IRCM (This power is required to flash the field of the alternator to allow it to generate electrical power. You have to have a magnetic field present in the alternator to cause electricity to be "formed". That is what the field does. You also need a conductor and relative motion between the two....but that is another subject.) Many connectors are NOT used on this module. Point being DO NOT disconnect the IRCM and expect the engine to run!!!!!!

The point of this exercise is to show you how important this module is to proper operation. You should consider removing the IRCM Connector and cleaning it and reapplying dielectric grease when you have problems associated with the various components affected by this device. Also...if you get in an accident (God forbid) and the front passenger side of the car gets smacked....you may or may not be able to drive away regardless if you reset the inertia fuel switch in the trunk or not if this device or its associated wiring has been damaged.

Information based primarily on early model SC's. I do not have the info available for the 94-95 versions with the dual fan set ups. There MAY be differences between various years of the early model as well. Consult proper technical inforation in troubleshooting problems on YOUR car.
 
I kind of figured it would be that. Is there any other option than replacing the IRCM everytime the fan goes out? I barely replaced mine a few weeks ago.
 
I replaced the IRCM again and my fan still does not turn on! Can anyone help on this one..is it the ignition switch or sum thing else? I am also waiting on another IRCM that I bought from a member so pretty soon my garage will be a IRCM junkyard! I read on the Haynes Repair Manual that the fan is controlled by the IRCM AND EEC-IV module. Should I replace the EEC-IV module?
 
Last edited:
Fan works!

After replacing the thermostat and filling the vent plug with coolant..may fan works! Probly just had air bubbles to begin with. Thanks for all the help guys. Hope this helps someone out in the future
 
Back
Top