Cooling fan problems.

[Lupo]

I was hot-rodding around the other night with my friend, and after I dropped him off, I noticed that the temp was way high. It was at the very top of the "normal" range, which has never been normal! My aftermarket temp gauge read over 240.
After I opened the hood, I noticed that the cooling fan wasn't even spinning. I turned on the "MAX AC" button, because I thought this automatically turned on the fan. No luck. I drove home, and once I was cruising on the freeway, the temp went back to normal. Once I was stopped at a light, the temp would rise again.
I started the car today, and the fan was working.
Has anyone ever had any weird cooling fan problems? Also, should the fan always come on when you use MAX AC?

<small>[ April 08, 2003, 05:01 AM: Message edited by: Lupo ]</small>

 

[ghostrider]

Yes the fan should always come on when you use any evironmental option that uses the AC compressor. With that said, it could be a loose wire or something on the fan itself. Or maybe the IRCM. Not sure if your IRCM is in the same place as it was when your car was stock. But if you notice the fan not working again, bang on it a couple times, A relay could be sticking. Hope this helps some.

 

[ghostrider]

And here is a link to one **** of a diagnostic procedure for the cooling fan circuit. The credit for this prcedure has to go to projectSHO89, Steve, http://www.shoforum.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=17;t=005071 Check it out. It might help.

 

[Lupo]

ghostrider:
Yes the fan should always come on when you use any evironmental option that uses the AC compressor. With that said, it could be a loose wire or something on the fan itself. Or maybe the IRCM. Not sure if your IRCM is in the same place as it was when your car was stock. But if you notice the fan not working again, bang on it a couple times, A relay could be sticking. Hope this helps some.

Thanks for the info!
I assume that the fan is entirely ECU controlled, meaning that it not hooked directly up to a temp switch, but through the ECU that acts on info from the temp switch?

 

[projectSHO89]

Yes.

 

[Lupo]

projectSHO89:
Yes.

Which line on the IRCM is the signal line from the computer to the fan relay? I would assume that this line grounds itself to turn the fan relay on. This would be an easy test with a test light if the fan was not coming on when it is supposed to, I could check this wire and determine that the ECU is actually sending a signal. From there I would diagnose the IRCM, or the fan itself.
The fan works fine when connected to direct power, so if it isn't the ECU, probably the IRCM.
Just to be sure, the IRCM is to the left of the ABS module, looking from the front?
Anybody have a picture?

 

[Huntervf]

I actually had this EXACT same problem on my 89. The fix was to replace the coolant temp sensor...the fan is electrically controlled but a faulty coolant temp sensor will not give the proper signals to kick the fan on when it's necessary. I also believe that if you unplug the sensor the fan will automatically kick on, so that would be an easy check to determine if the sensor is bad.

The sensor is easy to get to; it's located on the driver side rear portion of the engine; if you stand on the driver side of the car looking at the throttle body the sensor will be just to the right of it & a little ways down. I found it useful to disconnect the cruise control cable for easier access. You'll need to unplug the connector and you'll also need a large size (7/8 I believe) deep well socket to remove it. I would say it's much more likely that this is your problem as opposed to an indepth electrical problem. The coolant temp sensor is very easy to replace and it should only cost $30-$40.

<small>[ April 08, 2003, 06:43 PM: Message edited by: Huntervf ]</small>

 

[Lupo]

Huntervf:
I actually had this EXACT same problem on my 89. The fix was to replace the coolant temp sensor...the fan is electrically controlled but a faulty coolant temp sensor will not give the proper signals to kick the fan on when it's necessary. I also believe that if you unplug the sensor the fan will automatically kick on, so that would be an easy check to determine if the sensor is bad.

The sensor is easy to get to; it's located on the driver side rear portion of the engine; if you stand on the driver side of the car looking at the throttle body the sensor will be just to the right of it & a little ways down. I found it useful to disconnect the cruise control cable for easier access. You'll need to unplug the connector and you'll also need a large size (7/8 I believe) deep well socket to remove it. I would say it's much more likely that this is your problem as opposed to an indepth electrical problem. The coolant temp sensor is very easy to replace and it should only cost $30-$40.

Thanks. I'll check it out as I do more diagnosing.
I am kind of leaning away from the sender as the problem, because I turned on the MAX AC, as this should automatically turn on the fan regardless of temp sender, but it didn't.
The fan seems to be working for now, but it sure wasn't working the other night. Still I am not going to count anything out at this point.

 

[AutoSHO]

It may also be that the fan is just worn out (brushes). If the problem is intermittant but gets worse with time, chances are its either a faulty relay in the IRCM or its the fan motor itself going bad.

On second thought, I think the car is a turd. Might as well give it to me to keep from having to deal with any further problems!

 

[projectSHO89]

Which line on the IRCM is the signal line from the computer to the fan relay?

Read and follow step 2 in the procedure indicated. The answer is already there.

Steve

 

[yamahaSHO]

I second the ECT. I had a problem like this except my fan would come one with the AC and delayed until it reached the very top of normal. When it is faulty, it will cause the motor to run very rich, heat up fast, and delay the fan turn-on.

Also contrary to what HunterVF said, with the intake on, it is very hard to get to. But it can be done. I just replaced one on Rendyx's 2 weeks ago.

<small>[ April 08, 2003, 09:40 PM: Message edited by: yamahaSHO ]</small>

 

[Huntervf]

Is it in a different spot on a gen II? I changed mine in 5 minutes...you need to wiggle between coolant hoses a bit, and I found it easier to change with the cruise control cable disconnected, but I just unplugged it, used a large size deep well socket, short extension & ratchet...easy as pie shrug

 

[yamahaSHO]

No they are not different, it is the same on the Gen II. The first time I did it on my 95, it was difficult, but not as difficult as Rendyx's 89. I disconnected what I could, but I just could not get the damn wire bundle out of the way.

If you don't have a deep well that size like I didn't the first time. I used a long screw driver and a hammer and broke the plastic off. It was a little more difficult tightening it with a open end wrench.

Maybe you just have a better way of doing it. Now that I have done it twice, third time should be a charm thumb

 

[SHOtimer]

Huntervf, I don't know where you are buying a 30-40$ temp sensor at, let me know and I'll avoid it. I bought mine at Ford for less than 10$, and I bet you could prolly get it at Auto Zone for less than that.
Doug

 

[ghostrider]

Autozone has them for $17, which is where i bought mine when I replaced it. I think he was looking at SHO Nut of fod parts network.

 

[Lupo]

projectSHO89:

Which line on the IRCM is the signal line from the computer to the fan relay?

Read and follow step 2 in the procedure indicated. The answer is already there.

Steve

Check...pin 14. Got it.
Thanks!

 

[yamahaSHO]

ghostrider:
Autozone has them for $17, which is where i bought mine when I replaced it. I think he was looking at SHO Nut of fod parts network.

If you get the correct sensor from Torrie, it is still $30+

 

[Off Road SHO]

Are we talking about the ECT (engine coolant temperature) sensor that sends a signal to the ECU? Or the temperature sending unit that sends a signal to the temp guage in the dash? The ECT (the bigger one with two wires) tells the computer what the temperature is so that the computer can tell the IRCM (black box on radiator with a few relays in it) to send the power to the fan or fans.


Tom

<small>[ April 09, 2003, 08:57 AM: Message edited by: ThomasDooley ]</small>

 

[yamahaSHO]

I was referring to the ECT, I think someone else has mixed it up with the one for the gauge.

 

[Slo-Sho]

Huntervf:
Is it in a different spot on a gen II? I changed mine in 5 minutes...you need to wiggle between coolant hoses a bit, and I found it easier to change with the cruise control cable disconnected, but I just unplugged it, used a large size deep well socket, short extension & ratchet...easy as pie shrug

What he said. I only disconnected the wiring harness from the ECT sensor itself, nothing else.