How to fit thermo fan bypass switch

[Immortality]

nice post ther mate, however as it has been suggested earlier in this thread, if you need thermo fans to keep your engine cool when you doing 100km/h+ you have much more serious issues to worry about:bang: also try not to tailgate the guy infront of you, all your getting is the hot air from car infront.


most of the discussion in this thread also centers around the standard VN thermo fan, not some twin thermofan that you mention above.

you'll also note that using my method allows the thermofan to work in the Holden designed fashion including the AC and allows you to override at any time. my setup only uses one wire and single pole switch utilising the factory relay and fuse, can't be simpler then that:thumbsup: if you wish to use twin thermos, then simply wire the twin thermos in place of the factory one. simple.

 

[VN Wagz]

i have my thermos set to come on as soon as the engine fires, via a bridging wire in the relay box. This is a bit of a band-aid until i can afford a big JAR alloy unit and maybe another thermo, but there is a fe turbo V6s getting round with the same setup. Keeps my wagon on 1/4 temp all day long, unless im in stinking hot traffic, but thats rare.

When my manualised auto goes in, i'll be putting in the pro-ratchet that goes with it- inside the shifter case you can see where the shifter mechanism is set up to work with a microswitch for each gear (for these purposes, as well as nitrous, boost control.. etc)- this way i'll be able to run the thermos "on" manually until 3rd and 4th gear where im guaranteed to be at 60ks plus during around town cruising.

 

[Jaym]

Just went to do this to my vs after reading a few threads. Located the blue / white wire running from ecu to relay to ac etc etc. my problem is that my wire is live? With key on its 12v.

Any help?

 

[Sasha_85]

ok done a L67 swap and fan not working
if i connect this bypass switch up my question is

"Lets say i have a relay problem would this bypass switch even bypass the relay and still run the fan"?

 

[Cheap6]

Just went to do this to my vs after reading a few threads. Located the blue / white wire running from ecu to relay to ac etc etc. my problem is that my wire is live? With key on its 12v.

Any help?

That is correct. See post #69. Only with the PCM (or BCM for the low speed) switching the fan 'on' will the wire(s) be pulled low (= connected to earth).

ok done a L67 swap and fan not working
if i connect this bypass switch up my question is

"Lets say i have a relay problem would this bypass switch even bypass the relay and still run the fan"?

In short: no.

 

[Jaym]

So I'm right to earth it? Seems od earthing a positive wire :/

 

[UW1SH]

Iv had one of these in every single commodore i have owned (including the one i drive now) and not one has burnt the fan motor etc.. But mine is a different setup i run mine off the thermo fan fuse.. I only use it at lights and in traffic or heating up a bit but i dont turn it on when its hot i turn it on before it gets hot so then it doesnt get hot to start with.. that way its at the operating temp 90% time instead of hot/warm/hot/warm/hot etc if you get what i mean… if anyone is in brisbane area and need help doing one shoot me a PM and il be more then happy to come help you out :spot on:

 

[Sasha_85]

Iv had one of these in every single commodore i have owned (including the one i drive now) and not one has burnt the fan motor etc.. But mine is a different setup i run mine off the thermo fan fuse.. I only use it at lights and in traffic or heating up a bit but i dont turn it on when its hot i turn it on before it gets hot so then it doesnt get hot to start with.. that way its at the operating temp 90% time instead of hot/warm/hot/warm/hot etc if you get what i mean… if anyone is in brisbane area and need help doing one shoot me a PM and il be more then happy to come help you out :spot on:

i will send you PM after ive tried something besides cutting into the wire and if no good then mite have to get ya help

 

[UW1SH]

i will send you PM after ive tried something besides cutting into the wire and if no good then mite have to get ya help

No worries just as long as my ride is finished when you need it… Its off the road at the moment getting engine conversion but ALMOST done..

 

[Cheap6]

So I'm right to earth it? Seems od earthing a positive wire :/

It's not earthing it without a load on it; the fan relay is between the battery and the ECM switch.

If it were a light bulb in place of the fan relay, you would have: battery - light bulb - (ECM) switch - earth and would be putting another switch between the light bulb and earth, in parallel with the ECM switch. Until either switch is closed there will be battery Voltage wrt earth at any point in the circuit before the switch point.

If it makes you feel better, with the fan 'on', = A/C on, coolant temp. sensor disconnected, w' engine running or in diagnostic mode, ignition 'on', measure - backprobe with a dressmaker's pin - the voltage at C1 on the ECM wrt earth. You will see it drop from battery Voltage to zero as the fan relay is switched on.