Another FAN POSTING???

REILLY

Registered User
COME ON!!! Before anyone says anything. I'm here on this site b/c my nephew got a pretty good deal on a 1990 sc. He hasn't gotten his licence yet but will in november. I have plenty of experience building cars, but not this new. I told him that I would help him get things sorted out.... and now the car is at my house.

the Car:

1990 White , 82K miles, automatic. runs pretty well. problems include the fan not coming on. the radio wires all cut and after it heats up the thing bucks under WOT.

the parts car: 1994 SC 75K miles, hit in the drivers door and quarter... Totaled. lots of good usable parts but I'm finding that that lots of things were changed in 94year.

about the FAN:

did a search and read about two hours of posts regarding the cooling fan issues. here is where we are at.


originally switched fan from the 94 thinking that there might be a thermal switch on the fan housing or motor yhay went bad.

after reading found that there is module behind the headlight. I had two extras one from a 94 and another from an 89 swapped out twice and no auto fan.

topped off the fluid in the radiator and burped it. now when I pull the ECT sensor the fan comes on but at no other time will it come on, I used a temp gauge and the car is getting past 212 degrees and the fans do not come on. no fan either when the ac is on.


I have no check engine light on the car either. it will come on when I pull the ect but not on normally.

Changed out the ECT sensor still no auto fan.
all fuses and relays seem to be good so I'm not sure where to go next

Thank for your help ..Looks like a great site for this car.
 
1. The low speed fan does not come on until 220F, with the high speed kicking in at 228F.

2. The a/c system has to be working in order for the fan to kick on when its running, otherwise it won't turn on. If the compressor is working, then I would suggest replacing the IRCM... mentioned below.

3. When you unplug the ECT sensor, the EEC will command the high speed fan to operate, not the low speed... so at least we know the high speed works.

4. You need to use the parts from the same year of car including the IRCM module which is what is located behind the head light. These are a common point of failure in regards to the fan.

5. The low speed winding in the fan can be burned out.

Fraser
 
SURE let me know what you need. The 94 is at my nephews house but he'll have to sell stuff to buy parts for the 90.
 
Fturner- thanks for the advice. I'll have to hardwire in the low speed to make sure that is working , then make sure the ac is in working order. Maybe someone has a known working IRCM that needs parts off a 94 in trade?
 
So I Did A KOEO Test today with the factory fan wiring hooked up, and one of the first things that happened was that the fan cycled on but only one speed, I thought that it might do two speeds....not sure about that/

So after recording the numbers...42, 52,91,67, 18, something like that . one of the codes had told me of a ECT sensor over voltage. IS THAT A BAD ECT?

I took one from the 94 to replace it but maybe that one was no good either.

Anyway, seeing as how the fan cycled during the KOEO I decided to let the car get hot remembering that 220 and 228 were the numbers when the fan comes on and the highest reading that I was getting before turning the fan on with the hack wires was 212. It got up to the M on the Gauge and then the fan went on and cooled the car down. Maybe the coolant sensor for the gauge is wrong? any Ideas?
 
Ok, several things.

1. You only heard one speed coming on with the fan. There is suppose to be 2, first low speed, then it jumps to the high speed. You have already determined that the high speed works with unplugging the ECT sensor, so something is not allowing the low speed to work. Either the winding is burnt out in the fan motor, or the IRCM relay is shot (more likely). You can test the fan itself, by hot wiring it to your battery. Black is the ground.

2. If you have a code for the ECT sensor being 2 high, you either have a problem with your wiring in the car, or the sensor is bad. I'd get a new sensor and put it in. This would also explain why the high speed fan came on at 212 instead of 228. Do this and reset the codes and do the KOEO test to see if any new codes pop up.

Fraser
 
Fan Issues

Sir, I had the same problem with my 94. If you look at the height of the ECT and the height of the burp tube, you will see that the ECT is higher than the burp tube. In my case air was trapped under the ECT causing erroneous readings[air temp vs coolant temp] I burped air at least 10 times until all of the air was out of the system and now have both high and low speed. This was done after replacing both the ICRM and ECT which didn't help
 
Guys thanks for all your help on this. Im going to try these things and let you know how it goes.
 
Alright the low speed works when the wires are jumped. I changed out the IRCM and same thing happens. KOEO... only high speed fan comes on, this was a spare IRCM . I'm thinking that because it is usually the low speed that come on then that relay would go bad first. I have a few IRCMs and was wondering which relay inside wast the Low speed.

I have one IRCM opened and if the plug is on the left and the ballast resistor looking thing is on the top then which would be the low speed relay>? I can remove the high speed relay from another one and replace it. Is there any w ay to test the relays to make sure they are good?

The fans will come on but only after it is pretty close to Hot. shoulf the low speed come on when it is the middle of norm?

Could the Gauge be reading wrong because of the sensor for the gauge being off?

I had a simlar problem with my 94 mustang and the oil pressure sending unit needed to be replaced because the reading was low but before an engine rebuild I changed the sensor and it reads in the middle now.
 
You can't go by the stock temp gauge as that thing is all over the map depending what mood your car is in that day.

Fraser
 
thats why im wondering if maybe the temp is right where it needs to be to turn the fan on and I'm looking at an incorrect gauge.
 
Odds you got the code for the ECT sensor because you unplugged it when the car is running.. I believe each and every time i did that to ANY of my cars i got a ECT error code..

Also even when you pull the plug off the ECT sensor, i believe the Fan should quickly cycle to low speed for less then a second to get it going the directly goes to High speed, it will not stay on low speed for like 5-10 seconds before going to high.. Even with doing a Self test, it'll only do low for a split second..

So depending on how you you activating the KOEO test.. you should be able to hear the IRCM click then hear the fan start up then almost instantly after that another click from it (which is the IRCM starting the high speed)

Also on the KOEO test did you probe the low speed winding circuit with a test light to be 100% sure it's not getting power?
 
Also on the KOEO test did you probe the low speed winding circuit with a test light to be 100% sure it's not getting power?[/QUOTE]

good point. I'm going to try that.

if that circuit shows no power then that might be the IRCM? I would like to replace th eRelays in the IRCM but i'm not sure which one is the low speed relay.
 
I had the low speed stick on my '89 XR7, and i replaced the both fan relays on it, but i forget which was which.. there's only 3 in there, and there is a post some place on here showing possible PNs to replacement Relays that'll work..

If you know with pins the low speed winding and high speed windings got to (2 pins each at the IRCM? you should be able to track down the relay..

Also i just used some normal 40amp Automotive relays, but just trimed down the terminals until they fitted :p
 
I would like to replace th eRelays in the IRCM but i'm not sure which one is the low speed relay.

Its an integrated module....

attachment.php
 
Also even when you pull the plug off the ECT sensor, i believe the Fan should quickly cycle to low speed for less then a second to get it going the directly goes to High speed, it will not stay on low speed for like 5-10 seconds before going to high.. Even with doing a Self test, it'll only do low for a split second..

So depending on how you you activating the KOEO test.. you should be able to hear the IRCM click then hear the fan start up then almost instantly after that another click from it (which is the IRCM starting the high speed)

Also on the KOEO test did you probe the low speed winding circuit with a test light to be 100% sure it's not getting power?[/QUOTE]

The low speed windings are getting power. I did the KOEO test and hooked a voltmeter the fan wires and it is getting voltage on the low then high.

So maybe it is just the gauge sending unit that is reading wrong or the ECT that is not submerged totally and reading the air instead of coolant temp..
 
you said you've replaced the ECT sender??

Also typically the ECT sender is in the coolant circuit that for the heater, So if you have heat...... The Coolant temp Sensor (for the gauge) is on the thermostat housing so it itself can have a air pocket under it..

another thing you can do is tap into the to circuits again with some wire, and place a couple of lights on the cowl that show low and high speeds, and go for a drive??
 
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