Engine running hot, clutch fan not engaging

[cstern71]

I have been having issues with my temp creeping up with the air on. It is really only occurring in traffic in town. Outside air temperatures have been around 90F degrees with high humidity.

I have an ultra gauge (which I need to change the reading from celsius) and the engine temp has been getting up to 100 to 102C (212 to 215F). I wasn't sure if the clutch fan was coming on, but I'm was nearly positive I would hear it if it was. I know the fan can come on because it runs for about a minute at startup each morning and its clearly noticeable. Once I turn the air off and keep moving the temp will drop to normal around 95 - 98C. I do know the thermostat was functioning just fine during the winter according to the ultra gauge.

Most of the info I have read suggests the clutch fans are likely to get stuck on so I'm a little confused. Is it possible for the clutch fan to not be coming on when it is supposed to? Or am I wrong on when it should come on? I'm assuming I will just be replacing the clutch fan in the near future.

Thanks for any help guys.

 

[Mooseman]

Not always. Some will run like you said at first startup but that's just the silicone in it being stiff. Once all loose, it might not want to engage when commanded by the PCM. Sounds to me like the fan clutch is toast but you would need to do more tests. This thread talks about it extensively:
http://gmtnation.com/forums/topic/11157-engine-is-overheating/

 

[KNBlazer]

What year is your TV? Mine is an 04 EXT and have had the same issue WITH 2 new GM dealer installed fan clutches as well as the updated Calibration... I simply cycle the A/C on & off when it's hot and am stuck in traffic...

 

[The_Roadie]

Troubleshoot it electrically before changing the clutch. Front fuse #20, relay #45.

 

[Niklaus]

Check out the link Mooseman posted. I started that thread because I was having the same exact issues.

My thermostat's not right because it stays 1 tick below 210 which isn't normal but it does function. I don't want to replace it at the moment though.

One way you can test your fan clutch is to put on a heavy glove and or use a heavy rag to try and physically stop the fan clutch. If you are able to stop it then that mean's it is not locking properly which means it is no good.

I've yet to replace my fan clutch but to make sure I need to further see what's going to happen since I haven't been driving a lot lately, and temps are cooler.

 

[The_Roadie]

One way you can test your fan clutch is to put on a heavy glove and or use a heavy rag to try and physically stop the fan clutch. If you are able to stop it then that mean's it is not locking properly which means it is no good.

Just a note: This works only if you're already above 210 and the PCM is calling for the fan to be engaged. Mostly if you're not already overheating, the fan clutch will be disengaged and spinning weakly only via residual bearing and clutch friction. The only way to force the clutch to engage for a test if it's not already overheated (without having a Tech II or other high end $$$ scan tool) is to remove the relay and jump 12V straight to the fan clutch control input.

 

[Sparky]

I wouldn't be worried about 215F since that is only just a few degrees above the 210F. Doesn't seem to be near enough to worry about to me

 

[Mooseman]

Just a note: This works only if you're already above 210 and the PCM is calling for the fan to be engaged. Mostly if you're not already overheating, the fan clutch will be disengaged and spinning weakly only via residual bearing and clutch friction. The only way to force the clutch to engage for a test if it's not already overheated (without having a Tech II or other high end $$$ scan tool) is to remove the relay and jump 12V straight to the fan clutch control input.

Wouldn't turning on the A/C command the fan clutch to engage? I would think it should.

 

[KNBlazer]

Wouldn't turning on the A/C command the fan clutch to engage? I would think it should.

That was my understanding after the CAL update was flashed...

 

[cstern71]

Troubleshoot it electrically before changing the clutch. Front fuse #20, relay #45.

Wiring diagrams cause me to have massive brain farts. I will attempt to understand this though, but it may take a while.

Check out the link Mooseman posted. I started that thread because I was having the same exact issues.

My thermostat's not right because it stays 1 tick below 210 which isn't normal but it does function. I don't want to replace it at the moment though.

One way you can test your fan clutch is to put on a heavy glove and or use a heavy rag to try and physically stop the fan clutch. If you are able to stop it then that mean's it is not locking properly which means it is no good.

I've yet to replace my fan clutch but to make sure I need to further see what's going to happen since I haven't been driving a lot lately, and temps are cooler.

I know the clutch fan is capable of running since it does at startup, but from my reading it does that due to the valve being misaligned so I don't think the PCM commands it at startup. My temp gauge stays about a half tick to the right of 210. I thought my thermo might be bad, but the ultra gauge was reading 195 - 200F in the winter so I believe my thermo is good.

Just a note: This works only if you're already above 210 and the PCM is calling for the fan to be engaged. Mostly if you're not already overheating, the fan clutch will be disengaged and spinning weakly only via residual bearing and clutch friction. The only way to force the clutch to engage for a test if it's not already overheated (without having a Tech II or other high end $$$ scan tool) is to remove the relay and jump 12V straight to the fan clutch control input.

I wasn't sure at what temp the PCM calls for the fan. I've clearly broken 210 according to my temp gauge and ultra gauge reading from the ECT sensor.

I wouldn't be worried about 215F since that is only just a few degrees above the 210F. Doesn't seem to be near enough to worry about to me

Its not that 215 is that high, but if I don't pay attention I fear it could go higher. It will likely get hotter this summer so I could see it as a potential bigger issue.

 

[bobdec]

Just for info the attached shows the stock fan settings. The ETC and AC tables are an OR condition whichever occurs first starts the fan and the highest percentage between the two tables is used. . Note the AC only starts fan at 160 psi , that usually means it's above 75* F outside temp for the AC to hit that pressure. The ac may not run the fan on cooler days. The percentage (%) numbers in the tables are pulse width to the clutch relay, EG. a percent entry of 6 at 160 lbs in the AC table says the clutch relay will be picked 6% of the time or about 3.6 seconds out of each minute. Or at 210*F coolant temp in the ETC table says the clutch will be picked 7% of the time.

 

[cstern71]

Interesting stuff bobdec. Driving home today I hit 210F for a brief period of time, fan didn't come on. Outside temp of 85F. I'm not really having an issue yet, but if we start seeing temps of 100F this summer, I can just picture having to turn the heat on while sitting in traffic.

 

[KNBlazer]

Interesting stuff bobdec. Driving home today I hit 210F for a brief period of time, fan didn't come on. Outside temp of 85F. I'm not really having an issue yet, but if we start seeing temps of 100F this summer, I can just picture having to turn the heat on while sitting in traffic.

The radiator fan WILL ALWAYS be spinning when the truck is on, if it's not moving or barely moving, then you do need a new fan clutch... It's obvious when your idling and the fan is just not spinning the way it's suppose to...

 

[cstern71]

The radiator fan WILL ALWAYS be spinning when the truck is on, if it's not moving or barely moving, then you do need a new fan clutch... It's obvious when your idling and the fan is just not spinning the way it's suppose to...

It spins fine at idle. It engages at most startups, it just isn't coming on when I go over 210F. I had a clutch fan on my 2 previous vehicles and never had these issues. This one is foreign to me with its PCM control. I would update to the 2008 ones, but I am not ready to get a PCM flash yet and I don't want to live with the check engine light.

 

[IllogicTC]

It should be noted that the "fan desired" has a lot of positions available - I believe this is due to PWM control. Instead of acting like the blower in your HVAC where you have just a few predefined speeds, the PCM is capable of adjusting from between 0 and 99% clutch apply according to the charts.

The best way to truly determine if the fan is coming on when at a normal operating temperature in this case would be to use a multimeter with duty cycle (or get really fancy and get a scope). Notice the fan isn't really going to kick on where it sounds like you're flying a jet until you start hitting some pretty high temperatures, which is why I suggest meter testing to ensure it's receiving signal. Someone with a Tech 2 could arbitrarily tell the fan to apply at whatever they felt like, which would be great in further diagnosis.

190-220 fahrenheit is the accepted nominal operating temperature for the I6 engine.

 

[cstern71]

I guess maybe I was used to the clutch fan in my S10. It could be expected to come on any time the temp gauge went over 210.

I don't have access to a tech 2 unless I go to a shop and it doesn't sound like I have a bad enough issue to worry about it.

 

[bobdec]

To add to post #13, I used a heavy duty leather glove and did some experimenting a while back due to a P0483 (PCM was confused over ETC and AC control, and I got that resolved with a tune).

Testing ...requires a good glove and overcoming the fear of grabbing a spinning fan... With ac off starting the cold engine the fan ran at a faster speed for about 15 or so seconds after start, seemed to fluctuate on/off a couple of times. I believe that was due to cold fluid in the clutch that clears after running. Later thought it could be PCM testing the circuitry, in either case not significant, and I did not follow up. Let that high speed settle down before proceeding w/test.

As stated previously when idling the fluid in the clutch will keep it spinning even when not commanded on. This freewheeling effect was enough to actually keep the coolant temp in range, a click below 210, when the outside temp was about 65*F. Make sure your does that . At that time I could stop it easily with the glove.
I then held the fan stopped till the temp got up above 210* F. I then could feel the clutch activation was there as a slight pulse or surge from the fan, but it could still be easily be held stopped. As I continued holding the fan the engine got hotter and I could feel the fan surge increasing as I assume the clutch engagement pulse percentage was increasing. Not wanting to get it too hot, I let go and the fan sped up significantly. The glove only smoked when trying to stop it at that speed. Throughout the testing it's evident that there is quite a bit of delay and slush in the fan clutch fluid design, it speeds up slowly after commanded on and slows down slowly. But once it speeds up it gains a lot of momentum.

 

[KNBlazer]

Is there anyone out there that has had issues with 100 degree weather and their A/C on .... banged head on wall and decided to dump the electrically controlled clutch for a 2008 Old School clutch solving all of their issues?

I am strongly considering this... getting PCM tuned, scrapping clutch codes while I'm at it...

 

[IllogicTC]

I've found you can look to the sides of the top of the shroud to see some of the outer circle of the fan; I press on this with a rag to test the fan clutch rather than grabbing a blade, just to make sure if it IS hard to stop I don't damage a fin doing so.

In hot weather, your antifreeze/water mix plays a big factor, and should be 50/50 mix. For most winter occasions, 50/50 should still be good, but you can go with a mix of up to 70 AF to 30 water to help against deep freezes. Too much antifreeze to water will really kill you're cooling; if AF alone did proper cooling, we wouldn't really need water in the mix to begin with! I've read that specific gravity measurements are not the best method for HOAT-type coolants like Dexcool as you can get the same readings at different mixtures. There are test strips available for testing but I couldn't find a small pack for cheap at a cursory glance, just a big tub of like 70 strips for 30-some bucks.

 

[KNBlazer]

I've found you can look to the sides of the top of the shroud to see some of the outer circle of the fan; I press on this with a rag to test the fan clutch rather than grabbing a blade, just to make sure if it IS hard to stop I don't damage a fin doing so.

In hot weather, your antifreeze/water mix plays a big factor, and should be 50/50 mix. For most winter occasions, 50/50 should still be good, but you can go with a mix of up to 70 AF to 30 water to help against deep freezes. Too much antifreeze to water will really kill you're cooling; if AF alone did proper cooling, we wouldn't really need water in the mix to begin with! I've read that specific gravity measurements are not the best method for HOAT-type coolants like Dexcool as you can get the same readings at different mixtures. There are test strips available for testing but I couldn't find a small pack for cheap at a cursory glance, just a big tub of like 70 strips for 30-some bucks.

The coolant that's in the truck now was put in by the Engine shop that rebuilt my engine... so I'm pretty sure they've got their coolant mixtures down to a "T"... lol... this problem of A/C and Hot Days, I have had since 2005 at which time I was under the extended warranty and the dealer replaced two fan clutches as well as apply the PCM patch to increase cooling during hot ambient temps...

...and on stopping the fan, the method you use with the rag at the side of the fan is how I stop it as well... but at 210 it's not easy to stop... I should have tried it when it was 3 ticks past 210, but IT WAS TOO HOT TO GET OUT OF TRUCK..