always-on fan override switch wiring w/o firewall bypass?

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EvilStig

New member
So I've been looking through the wiring diagrams etc but haven't been able to find a solution yet that didn't involve re-routing wires from the radiator temp sensor through the cabin and putting them on an interrupt switch.

I would really like to not pass more wires through the firewall at this point if it can be avoided. Is there anything in the cabin (circuit breakers, wire junctions etc...) that I could potentially tap into for the purpose of overriding automatic control of the radiator fan and turning it on? preferably without pulling out the AC unit to get to the bulkhead wire looms....
 
underscore

underscore

Well-known member
You'd have to check the wiring diagrams but if I remember right turning on the A/C should trigger both fans to come on, so there should be something in the cabin you can tie to for triggering them. Alternatively the A/C line pressure switch will also trigger the fans and it's located closer to the firewall so you're not having to route as much wire in the engine bay at least.
 
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EvilStig

New member
underscore":41u0jh74 said:
You'd have to check the wiring diagrams but if I remember right turning on the A/C should trigger both fans to come on, so there should be something in the cabin you can tie to for triggering them. Alternatively the A/C line pressure switch will also trigger the fans and it's located closer to the firewall so you're not having to route as much wire in the engine bay at least.
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thanks I'll need to double check the AC circuit diagrams see if I can come up with anything.
 
FC Zach

FC Zach

Active member
underscore":fpsaa079 said:
You'd have to check the wiring diagrams but if I remember right turning on the A/C should trigger both fans to come on, so there should be something in the cabin you can tie to for triggering them. Alternatively the A/C line pressure switch will also trigger the fans and it's located closer to the firewall so you're not having to route as much wire in the engine bay at least.
Click to expand...

I believe you are right. I can vouch for the AC pressure switch at least. . When I first got my car I found that the fan (only one, PO removed AC) ran as soon as the key was in the on position. Because he removed all the AC components (specifically the pressure switch), the fan ran constantly, regardless of engine temp.

So with that said, I'd tie a switch into those wires.
 
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EvilStig

New member
FC Zach":2pwc90oq said:
underscore":2pwc90oq said:
You'd have to check the wiring diagrams but if I remember right turning on the A/C should trigger both fans to come on, so there should be something in the cabin you can tie to for triggering them. Alternatively the A/C line pressure switch will also trigger the fans and it's located closer to the firewall so you're not having to route as much wire in the engine bay at least.
Click to expand...

I believe you are right. I can vouch for the AC pressure switch at least. . When I first got my car I found that the fan (only one, PO removed AC) ran as soon as the key was in the on position. Because he removed all the AC components (specifically the pressure switch), the fan ran constantly, regardless of engine temp.

So with that said, I'd tie a switch into those wires.
Click to expand...

is the pressure switch in the cabin? if so, where?
 
FC Zach

FC Zach

Active member
Engine bay, passenger side corner of firewall, above EVAP connections, and beside engine wiring harness. Should be a two (maybe three, I can't remember correctly) pin connector.
 
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EvilStig

New member
FC Zach":30cjtd3v said:
Engine bay, passenger side corner of firewall, above EVAP connections, and beside engine wiring harness. Should be a two (maybe three, I can't remember correctly) pin connector.
Click to expand...

ah... nothing in the cabin then? the issue is running stuff through the firewall more than routing stuff through the engine bay.
 
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shadow_coupe

Member
Maybe someone already mentioned it, but wouldn't grounding out the fan temp switch work? Basically put a switch on the powered wire of the radiator temp sensor so it would think it was unplugged and just run the main rad fan? I know this doesn't help the firewall complication you mentioned but seems easy and minimally invasive as far as not needing a relay etc. It's on my list of mods to try...
 
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alltracman78

Active member
The fan switch is a switch, not a sensor. :)
It matters because they do different things. A sensor sends a varying signal back; a switch is just on/off.

What exactly are you trying to do?
 
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EvilStig

New member
I got it figured out.



the blue/black (really looks silver....) wire is the one to the fan switch, so I cut it, spliced in some loooong wires, and ran them through the firewall to the cabin, where I'm putting them on a toggle switch. Functionality tested, with the switch in the on position, the fans operate normally, with it in the off position, it opens the circuit and both fans default to always on.
 
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