How to fit thermo fan bypass switch

[RUN415]

Hi All,

I was driving over heavy corrugations and the air con 'popped'.
(eg: Sudden hiss - discovered it spat out coolant from the somewhat corroded accumulator thing at the front of the radiator.)

Not sure if it's related but a short while after that I noticed that the
thermo fan wasn't coming on when I turned on the air con...as it used to.

I bridged out the LO FAN fan relay and the fan came on...so it's still working ok.

SO my question is:
Is there any disadvantage (besides making the fan completely manual)
to just bridging out the relay socket with a switch???

For me it just seems easier (no splicing into wires etc) and I know it's going to work...
...as I must consider there is now another (air con?) fault somewhere?

Cheers.

 

[Immortality]

There is a pressure switch in the aircon system. The PCM would see this fault and not turn on the AC pump and also not turn on the thermofan as it is not needed but that doesn't mean the PCM won't switch the thermofan on when it's required once the engine reaches the required temp. Best to test by letting the engine idle once up to temp and verify if the thermofan comes on when the engine gets hot.

 

[RUN415]

Makes sense...and it's nice to know what's goin' on with the air con and fan.
I thought it was probably somethin' like that.

I'm a bit reluctant to test the PCM's ability to turn on the fan...
...as it's ALWAYS been way too late.
You can 'smell' the engine starting to cook before it comes on and it stresses me out.
I just hate doing that to my engine :")

I'm the only one who drives the car...so having the fan on 'manual' is not a problem.
So I'm going to proceed with my plan to wire the switch thru the relay socket.
It's only for occasional use anyway.

I guess I'll have to fix the air con at some stage...but it won't be any time soon.

Thanks Immortality. Cheers.

 

[Immortality]

Completely agree. In the stock tune the low speed fan comes on at 104° C and the high speed not until 108° C which is just bloody ridiculous. The best fix is to have the tune adjusted so the fans come on a lot earlier. On our L67 I run a 82° C thermostat and have the thermofans set to come on at 86° C staged (so there is a couple of seconds delay before the high speed fan comes on). Engine never gets over 87° C.

 

[VS_Pete]

As above.
That`s what I`ve got. The1 recommended it and did tune.
Temp hardly moves.
THERMOSTAT DAYCO 82° C
Part Number DT22A

 

[Deuce]

Completely agree. In the stock tune the low speed fan comes on at 104° C and the high speed not until 108° C which is just bloody ridiculous. The best fix is to have the tune adjusted so the fans come on a lot earlier. On our L67 I run a 82° C thermostat and have the thermofans set to come on at 86° C staged (so there is a couple of seconds delay before the high speed fan comes on). Engine never gets over 87° C.

I think my tuner has set my a/c fan to come on at similar temps.
Will log temps one day and see

 

[Draimond]

Low Fan
High Fan

1996 VS V6 Sedan

 

[gtrboyy]

Yep just an earthed switch somewhere easy to reach to blue/white trace,.

Also good idea to add another earthed switch for diagnostic mode...check for fault codes whenever you want.

 

[Havabigjuan]

View attachment 229326 Low Fan
View attachment 229327 High Fan
View attachment 229328
1996 VS V6 Sedan

really, really sorry for the thread revival

VS s2 Exec v6.....my low speed fan never kicks in....was told the output from BCM is fried

Just wanted to double check, is it as simple as finding yellow wire as in above pics, and grounding through a switch somewhere mounted on dash?

I actually wanted to have low speed fan on a switch, or come on when foot on brake pedal.... not sure if anyone has done this before??

Cheers,
Peter

 

[vc commodore]

really, really sorry for the thread revival

VS s2 Exec v6.....my low speed fan never kicks in....was told the output from BCM is fried

Just wanted to double check, is it as simple as finding yellow wire as in above pics, and grounding through a switch somewhere mounted on dash?

I actually wanted to have low speed fan on a switch, or come on when foot on brake pedal.... not sure if anyone has done this before??

Cheers,
Peter

I personally wouldn't have it on an independant switch or have the brake pedal operate it...Too easy to miss the temp rising and flick the switch/ dab the brake pedal to cool it down....