1st fan speed problems.

[aclwalker 3]

What could cause the 1st fan speed to be ignored and it go straight to 2nd speed? I've not tested it yet, but I'm pretty sure the wiring is fine as I've had this problem in the past yet the 1st speed always works when shorting the connector. But the fan just goes straight to 2nd speed, missing out the first, even though I'm sure the first speed runs on afterrun and other times.

 

In the past, my 2nd speed never used to come on, even though it worked fine when I tested via shorting out the wiring. The third speed used to come on first. I suspected the sensor was faulty but testing via a multimeter and boiling water showed it was working.

 

So I concluded that it was just sluggish coming on and the 3rd speed would trigger before the 2nd, so I fitted a lower temperature radiator sensor and the problem was largely resolved, with the 2nd speed coming on instead of the 3rd.

 

But now it seems to be that the 1st speed isn't working, on a relatively new sensor. Is it possible that the temperature is too high for the 1st speed, but not high enough for the second speed yet?

 

Should the fans always go 1st speed, 2nd speed and then 3rd speed (if really hot)?

 

I'm reluctant to put yet another radiator switch in.

 

Is it possible that the control unit isn't allowing the 1st speed to come on sometimes?

 

I suspect my battery is being depleted while running because the 2nd speed fan comes on too much and I suspect it's missing out the 1st speed altogether. It's difficult to tell though as you can't really hear the 1st speed while driving anyway.

 

These fans have got to be the most infuriating thing about this cooling system.

[Dazz_G60_Wales 0]

Its either the resistor on the fan itself or the switch on the control unit.

Do you know anyone you can borrow the parts off to test both

Ignore that thought you were on about heater fan lol

Edited October 17, 2017 by Dazz_G60_Wales

[a_riot 0]

What could cause the 1st fan speed to be ignored and it go straight to 2nd speed?

 

Is it getting hot enough to trigger second speed, or is second speed getting triggered at the first speed temp?

 

Stage 1

Controlled by the temp sender in the rad, directly to the fans

Switch On: 92-97 C (198-207 F)

Switch Off: 84-91 C (183-196 F)

 

Stage 2

Controlled by the temp sender in the rad, combined with info from the yellow temp sender via the fan controller

Switch On: 99-105 C (210-221 F)

Switch Off: 91-98 C (196-208 F)

 

Stage 3

Controlled by the black coolant temp sender, via the fan controller

Not listed in the guide above, but it kicks in at around 110-115 C.

For non-AC cars, stage 3 should never come on under normal conditions, if it does, you have a problem.

 

If it just gets hotter and hotter until 99-105°C is hit, then the fan's resistor may have failed so first speed just doesn't work. You can test all the speeds as you mention, and if first speed works, then I would suspect the switch which you can test as well. I've had bad luck with aftermarket switches, so I buy them at the dealer or a reputable source. If all 3 fan speeds are working, and the switch is fine, then you'll have some tshooting to do. Could also be a wiring glitch if its pinned out wrong. I had my fan spinning backward one day when doing some electrical tests on the VSS.

 

I've not tested it yet, but I'm pretty sure the wiring is fine as I've had this problem in the past yet the 1st speed always works when shorting the connector. But the fan just goes straight to 2nd speed, missing out the first, even though I'm sure the first speed runs on afterrun and other times.

 

I'd still check wiring. I think the afterrun is triggered by the relay not the switch but don't quote me.

 

But now it seems to be that the 1st speed isn't working, on a relatively new sensor. Is it possible that the temperature is too high for the 1st speed, but not high enough for the second speed yet?

 

Not really. As you can see from the temps above it works like normal set points. There is only 2 degrees difference between the highest first speed temp and the lowest second speed temp.

 

Should the fans always go 1st speed, 2nd speed and then 3rd speed (if really hot)?

 

Yes, usually. I guess there are corner cases where that might not occur, but typically my fan's first speed comes on at the first bold temp marker, then the second speed at the second bold market. Third speed I only ever hear when running A/C.

 

Is it possible that the control unit isn't allowing the 1st speed to come on sometimes?

 

No, I don't think so, if your switch is working. Looking at the wiring diagram the switch bypasses the fan relay for first speed and supplies power directly to the fan, so with a working switch and working fan it should come on. I guess the fan relay could override that and push it into second speed instead or soon there after or something weird. Might want to experiment by unplugging the fan relay. Check all fuses in the fan relay as well as #19.

 

These fans have got to be the most infuriating thing about this cooling system.

 

I've never had many issues after the fan recall, other than the fan resistors dying, but they can be repaired. You may have two problems at the same time as well.

 

This page I've found helpful, and quoted above.

 

https://sites.google.com/site/stoyneff/miscellaneous/the-vr6-cooling-system