91 supercoupe unique cooling problem

91redheadedbird

Registered User
First I would like to say that I am new to the group and it is my pleasure to be a member. I hope that somebody can assist me with this strange situation that my pain in the ***, but joyous car has provided me with. The cooling fan runs intermittently, but never when it is suppossed to. Sometimes it will be on all the time and other times it will never come on. I thought maybe it was the temperature sending unit, so I replaced that part. Unfortunately it did not help. I also checked all the similar threads on this site to help assist, but I did not find any direct relations. I have no other solutions except to take it to the garage. Is there anyone with suggestions? All are appreciated. Thank you!
 
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91redheadedbird said:
First I would like to say that I am new to the group and it is my pleasure to be a member. I hope that somebody can assist me with this strange situation that my pain in the ***, but joyous car has provided me with. The cooling fan runs intermittently, but never when it is suppossed to. Sometimes it will be on all the time and other times it will never come on. I thought maybe it was the temperature sending unit, so I replaced that part. Unfortunately it did not help. I have no ther solutions except to take it to the garage. Is there anyone with suggestions. All are appreciated. Thank you!

Check the cooling sensor located on the intake manifold. I think thats the one that sends the info to the fan computer. Try replacing it to see if that doesnt solve it. Also, try to run some codes to see if you can get any stored problem codes in your computer.
 
91redheadedbird said:
First I would like to say that I am new to the group and it is my pleasure to be a member. I hope that somebody can assist me with this strange situation that my pain in the ***, but joyous car has provided me with. The cooling fan runs intermittently, but never when it is suppossed to. Sometimes it will be on all the time and other times it will never come on. I thought maybe it was the temperature sending unit, so I replaced that part. Unfortunately it did not help. I also checked all the similar threads on this site to help assist, but I did not find any direct relations. I have no other solutions except to take it to the garage. Is there anyone with suggestions? All are appreciated. Thank you!

there are two Engine Coolant Temperature sensors on the SC. Did you replace both or just the one on the thermostat housing. The other is located on the heater core line the goes over the passanger side cyclinder bank.

Any error codes? (aka check engine lights)
 
RichM said:
there are two Engine Coolant Temperature sensors on the SC. Did you replace both or just the one on the thermostat housing. The other is located on the heater core line the goes over the passanger side cyclinder bank.

Any error codes? (aka check engine lights)


yes, I replaced both. The one sends data to the gauge cluster and the other one sends data to the EEC. I also chcked the computer for any error codes and it came up 11 (clear). Thanks for the suggestions.
 
Try checking the IRCM wiring to see if any wires are fried or disconnected. I also think there are some relays in there somewhere. I'm not sure though.
 
sonicman1634 said:
Try checking the IRCM wiring to see if any wires are fried or disconnected. I also think there are some relays in there somewhere. I'm not sure though.


yes there are. there is a high speed fan relay, low speed fam relay and one other. From what I can tell they are inside a big black box. Wasnt sure if I was to screw with the or not. I looked at the wires leading into ircm and they all look ok.
 
When the fan is running constantly, do you perhaps have the defrost or AC on? :cool:

Also, check the wiring harness that goes to the IRCM for any signs of tampering. Some people like to cut the control wire for the fan. It may be a bad connection. If the computer is unable to send a signal to turn the fan OFF, it will run constantly by default.

Is the EEC able to control the fan during KOER test?
 
XR7 Dave said:
When the fan is running constantly, do you perhaps have the defrost or AC on? :cool:

Also, check the wiring harness that goes to the IRCM for any signs of tampering. Some people like to cut the control wire for the fan. It may be a bad connection. If the computer is unable to send a signal to turn the fan OFF, it will run constantly by default.

Is the EEC able to control the fan during KOER test?



Dave, not sure about the KOER test, but the ac is not on nor is the defrost.
I did check the wires leading into the IRCM and they all look fine. Thanks for the advice
 
You sound like you know your way around the car, so forgive me if I get too basic. When the fan was failing on my 90 sometimes it would run and sometimes not. So look at the fan motor itself and make sure it's not overheating. Mine eventually shorted out and melted the wires about 3" from the fan motor. Why the fusible link didn't prevent this I don't know. Also, the IRCM (integrated relay control module) is located behind the passenger headlight a black metal box about 5"X7". It has relays inside that turn the fan low and high speed on and off. The IRCM has other functions also, so controlling the fan is not it sole job. It is possible the relays are sticking and not making or breaking the circuit at appropriate times. You can check the fan motor by direct connection to the battery. There are three wires, black=ground, smaller colored wire=low speed, larger colored wire=high speed. Connect each of the positive wires one at a time to see if both speeds work. Take care, the wires will get hot. Good luck, John
 
AnnivSpeCpe said:
You sound like you know your way around the car, so forgive me if I get too basic. When the fan was failing on my 90 sometimes it would run and sometimes not. So look at the fan motor itself and make sure it's not overheating. Mine eventually shorted out and melted the wires about 3" from the fan motor. Why the fusible link didn't prevent this I don't know. Also, the IRCM (integrated relay control module) is located behind the passenger headlight a black metal box about 5"X7". It has relays inside that turn the fan low and high speed on and off. The IRCM has other functions also, so controlling the fan is not it sole job. It is possible the relays are sticking and not making or breaking the circuit at appropriate times. You can check the fan motor by direct connection to the battery. There are three wires, black=ground, smaller colored wire=low speed, larger colored wire=high speed. Connect each of the positive wires one at a time to see if both speeds work. Take care, the wires will get hot. Good luck, John



Is the IRCM serviceable?
 
I've never heard of anyone successfully repairing the IRCM. There may be electronic gurus out there that have done so, but not heard of it. Good condition used units are available. Ask around. In fact, I have a good 91 IRCM. Email me at hobeaux@hotmail.com.
 
Lets back up a bit here....

XR7Dave "As usual" Makes a good point here in asking if the KOER "Key on engine running" test has control of the fan...It should be the first thing you notice while running codes weather it be a running or engine off test...The low and highspeed fans come on instantly. However if you got a "11" code after the test then I suppose this answers the question as I am almost sure that it would result in a failed test with codes.

Will the IRCM even pop a code in this scenario assuming it is bad? I would think that since it is part of the test to run the fans, if there was an issue it would have caught it during the test. Thinking out loud here...


Brad
 
cudaz101 said:
Lets back up a bit here....

XR7Dave "As usual" Makes a good point here in asking if the KOER "Key on engine running" test has control of the fan...It should be the first thing you notice while running codes weather it be a running or engine off test...The low and highspeed fans come on instantly. However if you got a "11" code after the test then I suppose this answers the question as I am almost sure that it would result in a failed test with codes.

Will the IRCM even pop a code in this scenario assuming it is bad? I would think that since it is part of the test to run the fans, if there was an issue it would have caught it during the test. Thinking out loud here...


Brad

Yes, actually the fan started coming on when we hooked it up to read the codes. Now it will just not shut off. But I had the problem before where it wouldnt shut off and then that turned into the problem of it not turning back on again until it was hooked up to the computer. NO ERROR CODES
 
"NO ERROR CODES"

Would not be the first time that a code wnet unreported/popped

I had a crank sensor going bad for weeks, had symtoms yet I had no codes, no CE light, nothing until the car was dead...Then of course if handed me the code...Nature of the beast...

Good luck
 
Unless there is some non-factory wiring, the only way that the fan can stay on is if a) the computer tells it to stay on or b) the relay in the IRCM is bad.

In scenario 'a' I am sure you would get a code for something manfunctioning.

In scenario 'b' it is easiest to swap the IRCM. They are available fairly cheap used (see above) or contact any number of other members (myself included). You can replace the actual relays inside if you can determine that is the exact cause. It does require some basic electronics testing/repairing capability.

I am quite sure that the answer lies within one of the posts here. Everyone has offered good information.
 
XR7 Dave said:
Unless there is some non-factory wiring, the only way that the fan can stay on is if a) the computer tells it to stay on or b) the relay in the IRCM is bad.

In scenario 'a' I am sure you would get a code for something manfunctioning.

In scenario 'b' it is easiest to swap the IRCM. They are available fairly cheap used (see above) or contact any number of other members (myself included). You can replace the actual relays inside if you can determine that is the exact cause. It does require some basic electronics testing/repairing capability.

I am quite sure that the answer lies within one of the posts here. Everyone has offered good information.


Yes, Good information has been offered by all and I do thank very much. I am going to replace the IRCM first as it is the easiest and cheapest solution next inline. Going to junk yard to see if I can find one. I will let everyone know what the outcome is. Thanks again
 
91redheadedbird said:
Yes, actually the fan started coming on when we hooked it up to read the codes. Now it will just not shut off.
Most likely, a sticking relay inside the IRCM. I had the same problem.. next time it happens, tap on the IRCM box lightly with some sort of tool and see if it shuts off.
 
TbirdSCFan said:
Most likely, a sticking relay inside the IRCM. I had the same problem.. next time it happens, tap on the IRCM box lightly with some sort of tool and see if it shuts off.
Had the same situation with my 90. Never replaced the box and havn't had the problem since. JJ
 
james5275 said:
Had the same situation with my 90. Never replaced the box and havn't had the problem since. JJ


Alright, I replaced the ircm unit and still have the same damn problem.
When I unplug the temp sensor, the fan does run. Still not sure what is going on. I am exhausted on ideas. Thank you everybody
 
When I unplug the temp sensor, the fan does run.
Ok, perhaps I am not understanding your problem. I thought the fan was running all the time??? Please explain again exactly what the problem is??? Thanks.

BTW, the fan is not programed to come on until 220 degrees.
 
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