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lgbirt 12-11-2017 02:17 PM

Coolant fans opposite functioning
 
A few days ago my MIL came on and scan showed P0128 indicating operating temp not reached within given time. About 10 seconds after starting engine both fans start up at high speed and continue to run until ignition is turned off. Scanner showed coolant and IAT sensors working normally. There are three relays: Main Fan, Fan Control, and Aux Fan. Pulling Main or Aux relay only stopped associated fan; pulling only the Fan Control relay did nothing. I removed all three relays and monitored Coolant Temperature to 195F. I then put all three relays back in and no fans run!!! It is as if the fans run only when NOT called for.....

Any ideas / suggestions appreciated! --

I did clear the codes and when I started again the fans did not run. I am sure the code will return as I had tried clearing code before. Is it possible that the P0128 code being set would force the running of the fans? If that is the case then perhaps I just have a stuck open thermostat.

JefferyC 12-20-2017 01:17 PM

Re: Coolant fans opposite functioning
 
[QUOTE=lgbirt;2261131]A few days ago my MIL came on and scan showed P0128 indicating operating temp not reached within given time. About 10 seconds after starting engine both fans start up at high speed and continue to run until ignition is turned off. Scanner showed coolant and IAT sensors working normally. There are three relays: Main Fan, Fan Control, and Aux Fan. Pulling Main or Aux relay only stopped associated fan; pulling only the Fan Control relay did nothing. I removed all three relays and monitored Coolant Temperature to 195F. I then put all three relays back in and no fans run!!! It is as if the fans run only when NOT called for.....

Any ideas / suggestions appreciated! --

I did clear the codes and when I started again the fans did not run. I am sure the code will return as I had tried clearing code before. Is it possible that the P0128 code being set would force the running of the fans? If that is the case then perhaps I just have a stuck open thermostat.[/QUOTE]

I "think" that code is thermostat.

lgbirt 12-20-2017 06:18 PM

Re: Coolant fans opposite functioning
 
I know what the code says: engine did not achieve required temp rise in allotted time! My QUESTION was would that code being set force the running of high speed fans??

fdryer 12-21-2017 06:05 PM

Re: Coolant fans opposite functioning
 
Unless the occasional GM tech familiar with Vues can offer his thoughts, you're left with one or two issues - fans turning on when the engine isn't overheated and the P0128 error code. If you keep these issues separate, you may answer the question yourself.

Previous Saturn models used a default program when a coolant sensor failed or signals sent to the ECM were not within the range expected and turned on cooling fans as protection against possible engine overheating. The best you can do other than paying GM to determine what's wrong is observing your reader, paying attention to engine startup and within the first 10-20 minutes of idling or driving - coolant temperatures. The service manual suggests noting two sensors, the intake and coolant temperature sensors. Both should be within a few degrees of each other with a cold engine at ignition on time (engine off). This is the first step in troubleshooting P0128 followed with starting the engine and observing coolant temps in the next ten to twenty minutes. If the coolant sensor temps rise to at least 160F within twenty minutes of idling or driving, the coolant sensor is operating as designed and points to a faulty thermostat. There are several P0128 errors in these forums - all related to a worn t-stat needing replacement. Depending on where yours is located on the engine will determine easy or difficult replacement. Addressing this error code is easier than second guessing if this has anything to do with cooling fans turning on with a cold engine and may correct it rather than continue guessing.

I've had to replace my t-stat with less than 80k miles, P0128 and it was a two day back breaking ordeal. It was buried in the 'V' section and required removing many upper engine parts. My L300 didn't turn on cooling fans when the error code occurred.

I would address the error code first then deal with the random cooling fans second if they return after replacing the t-stat.

CrewCab 12-21-2017 07:24 PM

Re: Coolant fans opposite functioning
 
There is a low speed fan resistor in the driver wheel well. See if it corroded and broke apart. That was usually the issue with the fans running on high speed.

[URL="http://www.saturnfans.com/forums/showthread.php?t=159303"]http://www.saturnfans.com/forums/showthread.php?t=159303[/URL]

The link above has a picture of a corroded resistor.

lgbirt 12-21-2017 10:09 PM

Re: Coolant fans opposite functioning
 
[QUOTE=lgbirt;2261131]A few days ago my MIL came on and scan showed P0128 indicating operating temp not reached within given time. About 10 seconds after starting engine both fans start up at high speed and continue to run until ignition is turned off. Scanner showed coolant and IAT sensors working normally. There are three relays: Main Fan, Fan Control, and Aux Fan. Pulling Main or Aux relay only stopped associated fan; pulling only the Fan Control relay did nothing. I removed all three relays and monitored Coolant Temperature to 195F. I then put all three relays back in and no fans run!!! It is as if the fans run only when NOT called for.....

Any ideas / suggestions appreciated! --

I did clear the codes and when I started again the fans did not run. I am sure the code will return as I had tried clearing code before. Is it possible that the P0128 code being set would force the running of the fans? If that is the case then perhaps I just have a stuck open thermostat.[/QUOTE]

I bought tstat and drained system to replace. After about forty minutes of trying to get at hose clamp I decided I did not have the time to do the job. So, I replaced to coolant and bled air. I noticed a small curl of steel (like a machining chip in the fluid I had drained and thought nothing really of it.
After about 30 miles driving (fans running normally) the MIL went out (I did not erase codes). I now think that the steel chip was lodging in thermostat and holding it open. Why it chose the time it did to come out is anybody's guess. The fact that the fans returned to normal operation after one start / run shut down cycle tells me that indeed the P0128 forces fans to run in self-preservation mode. -- thanks to all who replied.

fdryer 12-22-2017 12:44 AM

Re: Coolant fans opposite functioning
 
If you didn't throw out that piece of metal, can you post a picture of it? Snapshots from a cellphone may be too large with multiple megabyte files, too large to attach as thumbnails. In order to reduce file size acceptable for attachments, I suggest using your favorite image manipulating program to resize the image to around a megabyte or less and convert to jpeg format. I do this many times when copying large images and posting them here, including images from my camera or cellphone.

Hopefully, you corrected both errors with this one loose piece of metal.

lgbirt 12-22-2017 01:14 AM

Re: Coolant fans opposite functioning
 
[QUOTE=fdryer;2261896]If you didn't throw out that piece of metal, can you post a picture of it? Snapshots from a cellphone may be too large with multiple megabyte files, too large to attach as thumbnails. In order to reduce file size acceptable for attachments, I suggest using your favorite image manipulating program to resize the image to around a megabyte or less and convert to jpeg format. I do this many times when copying large images and posting them here, including images from my camera or cellphone.

Hopefully, you corrected both errors with this one loose piece of metal.[/QUOTE]
I did throw it out. As I stated, it looked to be a machining chip; curled up almost closed end to end, cylindrical about 3/32" diameter and about 3/32"high.


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