Quickshift_C5

The radiator cooling fans on my 01 ZO6 started randomly shutting down this weekend, making temps randomly climb and drop from it's usual 198F to as high as 232F. Seemed to me like the fan was randomly stopping, and this is exactly what I found when I watched the cooling fans.

After some searching here, I saw that the majority of these problems were faulty connectors. I separated the connectors and they appear perfectly fine, no sign of arcing or melting at all. EDIT: (Still doing searches) Found that there are low and high speeds for the fans and the fans are controlled by a ground signal from the PCM. There is also a ground pack located at the top right forward frame rail adjacent to the hood riser...I'll check the grounds tonight since it's a very intermittent issue.

I have a track day coming up on June 30th and would love to have this sorted by then. Any advice on what I could check or a place to start?

Thanks!

Quickshift_C5

Fantastic, thanks for the info! I'll check all of this over when I get a chance and check the actual fan operation. Will see if both are operating when they do turn on, and the specifics of when they actually fire up, or if it's truly random/intermittent. Will check relays/fuses/grounds as necessary and report back with results.

Quickshift_C5

Just haven't had the opportunity to look into this yet, but I'm going to do some testing tonight.

However, I'm going to join our local region for autocross tomorrow. I'd like to force the fans on during runs. Can anyone tell me how I can do that? Should be able to just turn on the a/c I think, but I'd rather not. I'm willing to install a cheap toggle switch temporarily to switch the fans on before runs. Curious what my options are...

Thanks guys!


edit: Nevermind fellas, found what I needed on RangerAcceleration.com

Quickshift_C5

Decided to take a look at this tonight and I think I came to the embarrassing conclusion that everything is working just fine...

Here is my understanding of the fan operation after help here and a bit of research:

AC Operation
1. Both fans turn on High Speed if AC is on and coolant is above 185F

No AC Operation
1. Both fans turn on Low Speed if coolant temp reaches 226F. Both fans turn off if coolant drops to 219F or car is above 35mph.
2. Both fans turn on High Speed if coolant temp reaches 235F. Both fans go back to Low Speed if coolant temps drop to 226F.


So, after watching the car carefully tonight and making note of exactly when the fans turn on...it's working exactly as designed. So what was the problem that got my attention? Well...I have two ZO6 Corvettes in the garage. This one I just bought, and the other I've had since 2009. The other car is supercharged, built motor, a long list of heavy mods. I was comparing the two cars directly in fan operation and temps...and I believe the other car I had the fans changed to 190F for Low Speed after a tune ages ago.

Oops. Thanks for the help guys, hope this helps someone else down the road.

foggy

You are correct except for the Fan Operation with AC on
They come on Low Speed when AC is on (under 35 mph).. Not High Speed,
unless engine temp or head pressure in AC system dictates
Either way, glad you got it figured out

Gordy M

What a lot of us who track our cars have done was to have the fans turn on at an earlier (lower) temp. Mine turn on at 209 and turn off at 198 for low speed and on at 215 for High speed and off at 206. This keeps the heat out of the engine during the warm up laps and helps cool the engine down during the cool down lap. When running, I only look at the oil temp. When it goes above 280 I run a couple a short shift laps until it comes down to 260 or below. The GM engineers in our club tell me it will run fine at 300F but why take a chance. Since I only put 3000 mile a year on the car and change oil twice a year, I don't worry about the detergents braking down.

Quickshift_C5

My tuner happened to show up at an autocross event I was doing 2 weekends ago. Had him change the fans while we were there and disabled skip shift.