Cooling fan turning on late

kenshi

Registered User
My car keeps running hot. I have flushed the system, had the radiator rodded, and replaced the thermostat. Today I flushed it again and went for a test drive. It stayed at around the M on the highway, but on low speed roads it started rising. As I was pulling into the driveway, it was pretty hot, probably close to the point where the check engine light comes on. Before killing it, I popped the hood to make sure the fan was working. It wasn't, but I pushed the connector for it together and it came on. So I left it idling to make sure it would cool off. The high speed fan came on for only a few seconds, and then the low speed fan for about half a minute, and then no fan. I looked at the temperature gauge and it was still above the M. Thinking the gauge may be inaccurate, I hooked my voltmeter to the ECT and it read 0.43 volts, which corresponds to about 215 degrees. I'm pretty sure that's hot enough for the fan to be on. I played with the connector again but no fan. I pulled the ECT connector and the fan popped right on. I plugged it back in and the fan shut off. So apparently, part of the problem was that the connector for the fan was loose, but also the computer isn't turning on the fan when it should. When I finally killed it, the coolant was boiling. I have recently replaced my ECT sensor and my sender unit. I just can't figure it out. I need some help with this ongoing problem.
 
Stock fan on temp is 220 deg. High speed fan is 228 which is hot enough that if you shut the car off after it has hit 228 deg it will after-boil.

But as to your other problems, the fan connector is probably shot. They get so hot they melt inside and the connection gets corroded.
 
If you pushed the connector together and the fan came on... there's your problem.. The connection is bad and even if it came on, there's no guarantee that it will work properly from then on. Try pulling it apart and looking carefully at the contacts and clean them well. I'd recommend brake cleaner. See if you can tighten the pins up. Next time it heats up, grab the wiring harness and wiggle it around. That might tell you if its a loose or broken wire. :) My guess is your ECT is fine. Also make sure you have a new radiator cap.
 
XR7 Dave said:
Stock fan on temp is 220 deg. High speed fan is 228 which is hot enough that if you shut the car off after it has hit 228 deg it will after-boil.

I didn't think it would wait that long for the low-speed fan. Anyway, either this fairly new ECT sensor is bad or my water is boiling before it even gets to 220 degrees. (I don't know what temperature the water is supposed to boil at while pressurized. Oh yeah, I only have water in it right now because I don't want to put in more anti-freeze until I get things straightened out.) It just doesn't seem right for there to be bubbles running up the overflow reservoir, the temperature gauge to be about 3/4 of the way to H, and yet the computer still doesn't tell the fan to come on. Maybe I should try putting the old sensor back in or try the one from my LX.

And yes, I probably need a new connector. This isn't the first time I've had to push it together to get the fan to work. However, it's not my only problem since the fan works when I unplug the ECT. As much as I wish it was, the problem is not as simple as that.
 
Well I changed ECT sensors. It's a little better. The fan comes on just above the M, before the water starts boiling. When I drive around, it stays around the R and M. That's still a little hotter than it ran a few days ago. It stayed on the N and O. I'm not comfortable with it, but I don't know what I can do.
 
kenshi said:
......................I don't know what temperature the water is supposed to boil at while pressurized.
.....................
Have you replaced your radiator cap? It may not be holding the correct pressure (16 psi).
 
Sorry, not trying to hijack this thread, but ...

Strange how all SCs start running hot over time. Dave, since you've tuned a bunch of these, how much impact do clogged cat converters contribute to higher engine temps? Do cars w/ exhaust work or new cats run noticably cooler? I assume you must notice when you program chips for fan set points. Anyone else notice any correlation?
 
Guage Reading

XR7Dave, Or anyone that knows..

Given that the stock guage is not the most accurate thing in the world..

Question, approxamately where should the needle sit on that guage to be considered good opporating temp..

Mine sits right on the N and O while driving. Climbs a upto the R when sitting for a short period of time.. and when the temp is up.. my fans never come on..

I have had N/A Cougars with 3.8's and the needle rested below the N. would this be ideal for our SC Cars as well?...
 
Typically the gauge will read at the 0 or lower if everything is good. Our motors are more sensitive to temperature than a regular engine and therefore respond better to lower engine temps. If you have a chip and 180 deg thermostat the temp will read below the N under most conditions.

I would not drive an SC with the gauge in the M. Most likely the headgaskets are leaking which is resulting in too much pressure in the system and air locks which prevent proper coolant flow. This is particularly true if the gauge fluctuates a lot or air bubbles appear in the overflow.

If the gaskets are indeed leaking, further damage can result from further attempts to bandaide the problem. Air pockets cause extreme hot spots in the heads which can lead to cracking etc. I recommend that you have your coolant checked for hydrocarbons.
 
I clipped the #14 wire to get my fan to come on.....

Now the stock thermostat has complete control over engine temp......

My gauge sits straight up at the 12 o'clock position between the O and the R....

It never moves, no matter how hot it gets outside or how hard I am driving.....

I can assume that on my gauge this would be 195 degrees......right?
 
Actually, the thermostat can only controls the min coolant temperature. It is designed to CLOSE when the coolant gets too cold. This helps with quick warm ups and ensures the coolant stay at a minumum temp. Air flow across the radiator increases it's ability to remove heat from the coolant.

Clipping the #14 wire keeps the low speed (LS) fan on at the cost of taking away control from the ECA. One of the the things the ECA does is make sure that only one fan runs at a time. On the rare occasion the LS fan is not capable of bringing down the coolant temp, the ECA will trigger the HS fan relay on and the LS fan relay off. BUT, if the #14 wire is clipped, the LS relay will remain on the same time the HS relay is energized. I'm not sure what will happen to the fan if both FAN coils come on together, but I'm pretty sure the fusible link will blow killing both fans.

Sorry .... just playing devils advocate. I would at least put a switch on #14 so you can give control of the fans back to the ECA if the LS fan is not cooling enough doing so BEFORE the ECA triggers the HS fan relay.
 
I understand what you are saying......

The reason I clipped the #14 wire was because neither fan was coming on and I have replaced both the fan and the IRCM......

I am thinking my problem is with the ECA........

Sitting in traffic, the temp gauge would peg and the check gauge light would come on...... :eek:

Driving on the highway, there was no problem.....

With the low speed on all the time, the coolant will be cooled by the radiator as it was designed......

The thermostat now regulates the coolant flow from the engine to the radiator.....

If the radiator is getting the coolant too cool, then the thermostat closes a little......

I have yet to see the needle go past the 12 o'clock possition.....

The needle on the temp gauge remains rock steady in the same position all the time.....
 
You can check for proper fan function by using jumpers at the connector and doing the KOEO test. I summarized the procedure on another thread. If both fans function, the cause is not the fan control circuit, but probably a singnal input problem from one of the many sensors (or the car really runs hot).

I am wondering what is the root cause of all these SCs running hotter now as they age and wondering now much clogged cats contribute to the problem. No one has been able to correlate the two somehow.
 
There could be something with clogged cats and over heating.....

Most of the problems that I and others seem to be having is more of an electrical problem of some sort.....
 
90 SC Coolant Fan Problem

Can you offer some assistance regarding my coolant fan notcoming on as it should. Neither the LS or HS works. my AC is also not working. I understand the fan works through the AC. Is this Correct. In any event, I replaced the ECA i guess this is the box in front of the air flow black box, same results after the swap. my connector is good and the fan works straight off the battery. i have noticed when i unplug the sensor(is this the ECT?) behind the DIS module the fan comes on.

How do i rectify this problem as i need to do highway driving soon and don't want to rely on using the LS fan constartly on the 2 hour trip. also, where are the LS and HS fan relays located? Maybe these relays are bad and are causing this problem. Please advise ASAP. Thank You





tcshum said:
You can check for proper fan function by using jumpers at the connector and doing the KOEO test. I summarized the procedure on another thread. If both fans function, the cause is not the fan control circuit, but probably a singnal input problem from one of the many sensors (or the car really runs hot).

I am wondering what is the root cause of all these SCs running hotter now as they age and wondering now much clogged cats contribute to the problem. No one has been able to correlate the two somehow.
 
This is a tough one. I have feeling your fans are probably both working as they were designed. If this is the case, you might be better off cutting the appropriate wire to the IRCM (You can do a search on IRCM to find this procedure).

Yes, the fan works when the A/C is turned on, but ONLY if the A/C if full of freon. If you’re A/C is low on freon, the A/C will not come on, hence, the LS fan will not come on.

The IRCM is in front of the air box, which contains both of the fan relays.

I would have guessed the fusible link to the IRCM was shot, but you said the fan comes on when you unplug the ECT, so that means the relays are getting power.

You should at least check the IRCM and fan combination by running a quick check with jumpers and the Key On Engine Off (KOEO) test. Here is the procedure from another thread:

Here's how I determined IRCM and fan both worked normally:

I used non insulated spade connectors and 3 pieces of insulated 14 ga wire to make jumper cables running between the female fan connector and the mating male connector on the fan cable harness. I suggest making the wire just long enough to reach between the fan connector and the car battery (I'll explain later).

Leaving the black ground jumper in place, disconnect one of the other power jumpers, then run the KOEO test and listen for the fan to come on. Reconnect the power jumper then disconnect the OTHER power jumper and repeat the KOEO test and listen for the fan to come on again.

If the fan came on both times when running the KOEO test, your IRCM and both fan coils are working fine and you problem is elsewhere. The KOEO test actually functions both fan coils, but it happens kinda fast making it hard to tell which fan speed(s) turns on. Doing it this way, you are sure each functions.

If the fan fails to run on one of the KOEO tests, disconnect the 3 wires from the male side of the harness leaving all three connected to the fan moter. Touch the ground to the negative battery terminal and each of the power wires to the positive battery terminal ONE AT A TIME. By the way, this is gonna spark because if the current draw, so be warned! If one of the fan speeds still does not work, one of your fan coils are dead and you need a new fan moter. If both fan speeds work when connected to battery ... your IRCM could be the problem (or the problem can lie upstream of the IRCM).



Fordrunner38 said:
Can you offer some assistance regarding my coolant fan notcoming on as it should. Neither the LS or HS works. my AC is also not working. I understand the fan works through the AC. Is this Correct. In any event, I replaced the ECA i guess this is the box in front of the air flow black box, same results after the swap. my connector is good and the fan works straight off the battery. i have noticed when i unplug the sensor(is this the ECT?) behind the DIS module the fan comes on.

How do i rectify this problem as i need to do highway driving soon and don't want to rely on using the LS fan constartly on the 2 hour trip. also, where are the LS and HS fan relays located? Maybe these relays are bad and are causing this problem. Please advise ASAP. Thank You
 
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