Friends,
I ran into some cooling fan issues the other day and I'm wondering if this scenario rings any bells.
I drive a 2007 C6 Base and live in Dallas, Texas area.

The other day, I was driving around and my temps were as usual in the 202-210 range around the city with red lights, etc. All of the sudden, while at a red light, I see the temps go up to 223. hmmmm. This caught my eye because it has never gone that high even during the Texas summer, and this was not a very hot day. ( 217 or so is as high as it goes when stopped in a parking lot waiting for the wife to do some shopping while I wait for her). Once I started moving again, the temperature started going down. I stopped at the grocery store, came out several minutes later, and when I started the car, the temp went to 235. When the engine started, the fan started too, and brought the temperature down to more normal numbers. Normally, I hear the fan staying on even after shutting off the engine, so when I restart it, it's relatively cool. But, not this time....

Any thoughts???
Obviously the thermostat is working.
Obviously the fan is working.
Coolant level is ok.
No codes detected by my code reader.

The thing is that in two years I have owned the car, I have never seen the temp go that high (235) when starting the car even with a hot engine.

Is there a switch that turns the fan ON/OFF after you shut off the engine that could be malfunctioning that is independent/different from the switch that turns the fan ON when the engine/AC is running??

Any suggestions will be greatly appreciated. (My wife's suggestion: it still runs, so keep driving it... hahaha)

Joe

 

You may have sucked -up some grass clippings. My 08 started running a little warm, sure enough there was a lot of grass, etc. in radiator and condenser. Correct fix is take them out to clean. I made a 3' x 1/2" long right angle sprayer. It goes down between radiator and condenser. It does an OK job. Just have to use it often, I seem to drive through many landscapers' crap!

 

OK, understood. I can easily check the radiator, etc for debris.
But, how does that affect the fan from turning ON/OFF after I shut the engine off??

 

Crap in the radiator fins would not affect fan turn on, after shut-off. My fan seems to come on when it wants, every now and then. But I can tell a small increase in temp, after driving through leaves/grass. BTW I run a 160 stat. When I start seeing 220+, I know it is time for a cleaning.

 

Yup, and I have been wondering about the 160 stat too. I've been reading about them and I have seen more thumbs up than thumbs down in that regard. Next time I take it to the shop for whatever reason, that may be one thing I will add to the list.

Thx

 

You may have a connector that is loose or corroded causing the fans to act erratic. Could even be a ground issue as well. Check these starting at the fans and work back. Should be able to get a wiring diagram from someone on the forum. I don’t have same. My 2008 has similar issues when I stop at a store or the like. Heat builds up and when I start it I get a high temp which goes away quickly as I motor down the road. I checked last time it did that and fans were running when I raised the hood but I couldn’t hear them inside the car. I cleaned connectors I could find and it seemed to help.

 

Not sure how to test it but you should have a cooling fan module.

Google....

ACDelco 15-80803

 

Coolant temps depend on the fan table if you are not moving fast enough for sufficient air flow. This is the stock fan table.


Given that the fan doesn't fully ramp up until 225, seeing 223 isn't surprising. I've seen that even with a DeWitts rad. The 160 stat will only delay the inevitable for a few minutes if you are stuck in traffic. The only way to get it to run cooler is to modify the fan table so that it ramps up sooner. Do this at the risk of melting the fan connector. In your case, I'd be checking and cleaning the fan connector contacts. I do this every oil change. Checking for debris blocking the air flow is also a good idea, as others have pointed out.
There is also some interaction with the pressure in the A/C system that will cause the fan to ramp up sooner. I take this to mean that if the A/C is working harder, it gets an assist from having the fan work harder too.

 

ok, all these are great suggestions. I'll start with the simple ones first, such as cleaning the connector, fan, and radiator.
I will post the results.
Many thanks

 

Well,
I wonder if the air filters were the guilty parties or not. But, while cleaning the fan, connector, and radiator, I figured I check the air filters. Ordering replacements tonight.
I drove around town and temps were perfect, 194-198 on the highway. Then, I parked in the driveway for about 15 minutes and the temp never went higher than 219.
So far so good. Many thanks for your suggestions. I really appreciate it.

 

Pull the radiator fan power connector, to see if it starting to melt.
Red dot is on the connector,
Attachment 48334002

Hence if fan table values where lowered, it causes the fan to pull more power than normal, and can melt the connector.



Short of that, start checking the front of radiator for debris that are blocking air flow through them, and may have to pull the A/C condenser forward to clean between it and the front of the radiator itself as well. Hence when you changed the air filter, may have bumped the two to knock some of the crap that was sistered between the two that was blocking air flow.

 

Thanks, Dano.
I checked the connector and it looked normal. Not melted, etc.
I cleaned the air filters until new ones arrive.
I used compressed air to blow the radiator area, fan blades, etc . Not easy without being able to lift the car, but I did the best I could.
Like one of the guys mentioned, I'll get it properly cleaned when we lift the car for an oil change.
The car ran very nice yesterday. No issues.
Im grateful for all the assistance.

Joe

 

The fan connector is a known issue. Often the initial failure is intermittent - sometimes you'll run hot(er) and sometimes you won't. This can keep you scratching your head. When you separated and reseated the connector halves, you may have cleaned the contacts enough to make it work properly, for the present. So next time you get a chance, it would be a good idea to take another look at the connector. If it truly looks OK, at least hit it with contact cleaner and reassemble with a little dielectric grease. Then it should work fine until it eventually burns up as they all seem to do. I've been around the block twice with this. First time I replaced the connector, second time I hard wired the fan and no more drama. Good luck

 

I will make sure to check the connector when I have the oil changed, every year, as a matter of routine, in addition to blowing/cleaning the radiator, AC condenser, fan blades etc. Temperature issues seem to be more frequent with these cars than others, so it will be worth to take the time and get it done.

This was a great "experience" because the temperature issue was driving me nuts, and now I have a little better idea of what to look for before I take it to my mechanic and spend a money asking them to do what I could have done myself.

Many thanks!

 

South Texas 107 deg middle of day, doesn’t go over 220 w/ stock thermostat and AC blasting.

Changed thermo this past weekend to a 160 w/ water wetter and just idling the highest it’s gone is 187. I haven’t driven it around but I’ve cycled the coolant a few times just letting it idle w/ a cam.