Repair-It

I've been noticing that the fans don't turn on as the weather warms. I finally was annoyed enough this morning and went to fiddle with the fan controller. I turned the adjustment screw in both directions and nothing. Then I noticed the coolant temp was creeping up so I kicked on the A/C to turn the fans on. A few minutes later, I realized the fans still weren't running and it was over 240°F. I shut the engine off.

At this point, all of the heat/pressure started going past the relief of the radiator cap, filling the overflow tank. I watched the level get higher and higher, and higher. Until it started pissing out all over the ground. Nice.

It may be that the fan controller completely died, so I ordered a new one:
http://www.summitracing.com/parts/der-16759

Fortunately the harness is modular so when I get it, I can just plug it in. Actually, not quite - I need to replace the fuse holder since I broke off the fuse while trying to determine if it was blown. Neither of the fan fuses are blown and I doubt the relays failed at the same time. Either the 12V ignition switched power source stopped working (from fuel pump relay), or the controller itself just is dead. Or I guess it could be a ground issue. I will probably just rig up the new controller quickly and determine if that is the only issue. If not, I will troubleshoot in depth.

As with most things on this car, all of this crap is aftermarket. If the car still had the original mechanical fan, none of this would be an issue. Not saying I regret doing electric fans or anything - I will fix it. But it is interesting that my theory continues to prove out. When you start with some German garbage, you can mod your way to reliability. But when you start with something pretty simple and bulletproof, modifications probably decrease reliability. A thought for the ages.

I guess you shoulda kept the mech fan and a wrench in the trunk for that one!

How do you know it's not the fan itself?

Mechanical fan really can't be bolted in because it will hit the electric fans. Plus I have no shroud at all so it wouldn't work very well.

I doubt both fans failed. Both fuses were fine.

My guess: either the 12V supply (tapped from the fuel pump relay) somehow failed/broke, or the controller died. Now I had thought the override signal (from the A/C clutch) bypasses the controller electronics and just triggers the relay directly, but it may have some logic inside that needs to do something.

Estimated delivery: Saturday.

Before I left work yesterday, I checked the coolant level. The overflow tank was completely empty so I checked the radiator. It was only an inch or two down, so I didn't even bother to get coolant. If I didn't know what happened, I wouldn't have noticed anything on the drive home. Pulled in the driveway to get the mail, coolant temp at 194°F. It just needs the fans to work when stopped for a while.

That's great. I was gonna ask what you were driving until it arrived.. But the answer is the Caprice.

Because B-Bodies are awesome, and even with 300k and no cooling fans, you still drive them.

I mean, the radiator fans probably work on the CTS-V too..............

Yes. And today I drove the CTS-V.

Drove it to lunch, too. 4 engineers, up a hill, still engaged traction control in 1st gear. Strong today, at 53°F.

Needs more turbo. Beg my pard.

kevm14 wrote:Needs more turbo. Beg my pard.

I just had to quote this...

Installed the new fan controller yesterday. Fixed.

My process went something like this:
- Disconnect harness from old fan controller.
- Make sure fuse holder is sound - I had to bend the receptacle a little to grab the fuse better. I was going to replace this but it should be ok. Install a good fuse.
- Start engine and see if there is 12V ignition power at the fan controller yellow wire. There was.
- Look at wiring diagram - I needed to short the red and black wires to trigger the relays. I did so with a paper clip and the fans came right on. So far the wiring was sound.
- Install new fan controller. Pretty simple - unscrew the two sheet metal screws and remove it, install new one.
- Plug everything in. Next test was to try the A/C override. That also worked, turning the fans on with the compressor. Score.
- Wait for warm up, adjust temperature setting to taste. Kicks on at around 215, shuts off at 195 or so. Pretty large hysteresis but meh.

Done.

I looked at my order history and I ordered this one almost exactly 3 years ago. 1 year warranty...

Glad it all turned out well for you.

Looking at this gives me an idea... This kit is cheaper than just the wiring for the innovative wiring conversion kit. And it also allows me to avoid messing with the primary fan relay that was repurposed on my car for AC.

My secondary fan is the one that comes on for AC, so I wouldn't need any controller for the second fan. I could theoretically use this or a simpler controller to replace my mechanical fan with the one from the caprice, no?

Heck, I could even set the limit very low to compensate for the mechanical fan being on all the time.

So you're saying replace the mechanical fan with the primary from the Caprice and control it with this? They do make one with a 3/8" NPT threaded sensor which I would recommend if you can find a place to screw it in. It is the same thing as mine but with a different sensor.

Your secondary is controlled by the PCM, yes. But it comes on at a high temp, or a high A/C condenser pressure. If it comes on "a lot" with A/C use then I'd suggest your mechanical fan isn't doing that great of a job.

I know the relay situation would require delving back into but I would have a hard time recommending something aftermarket when your stock PCM will already do it. Maybe you can make the kit yourself for far less?