TheSamba.com :: View topic - I want a simple way to have a switch to control the rad fan

Tue May 07, 2019 4:28 pm

Vanagon 1987 GL, no AC. I looked at a lot of threads but mostly were dealing with AC or other things not related to my van. Want to be able to start the radiator fan when I feel like it , I will install a switch just under the hazard rocker switch, I have a spot open
Here is the wire Diagram, it may show side ways but will eventually correct itself, it's a photo bucket thing

What do you think?

Marc..

Tue May 07, 2019 4:53 pm

decide what speed you want (hi or low) and tap into that wire. add power and you're done. fairly easy and if done properly easily reversed

Tue May 07, 2019 5:03 pm

Adding power to position 2 runs the fan on low. Adding power to position 1 will energize the high speed fan relay. I’m referencing your diagram and the thermal switch.

You will be molesting factory wiring. If you don’t do it correctly, i.e 3m scotch lock connectors, moisture will find it way into the wire causing corrosion. At that point, you could actually cause the fan to stop working.

Tue May 07, 2019 5:30 pm

Super easy mod, just splice a toggle switch into the high speed line (I don't know why you'd want to toggle low speed) at the rad thermoswitch. I put the toggle switch in the blank switch spot on bottom right side of the cluster. It's nice to have for prepping a little cooling before or after long grades. I wouldn't overuse it though. The van cools itself just fine without interference for the most part, and there's no need to cool stuff down below 180*.

I guess I should add, if you don't have a oil temp gauge, don't do this mod at all. You shouldn't be randomly guessing when you feel like overriding the stock cooling system...

Or, you could splice in a two-speed switch and tap into both low and high speed. But, that's really overkill and will pull you out of the driving experience too much, imo. Heck, a toggle switch at all is kind of overkill... Whatever floats your boat, though!

Tue May 07, 2019 5:37 pm

Marcq wrote:
Here is the wire Diagram, it may show side ways but will eventually correct itself, it's a photo bucket thing

Might as well just throw it in the trash. Photobucket has wiped out a lot of useful content here. Better to upload it here.

Tue May 07, 2019 5:47 pm

skills@eurocarsplus wrote: decide what speed you want (hi or low) and tap into that wire

Tap into that wire? What does tap means?

Marc..

Tue May 07, 2019 5:52 pm

Paulbeard wrote:

Better to upload it here.
Don't want to upload a content that is not relevant yet

I have a lot of pictures on PB I don't mind paying

Marc..

Tue May 07, 2019 5:57 pm

Phaedrus wrote: You shouldn't be randomly guessing when you feel like overriding the stock cooling system...

Oh no!! Just when I'm stuck in traffic at 100 degrees

Marc..

Tue May 07, 2019 6:23 pm

Not to abuse Marcq, but I don''t understand the rationale. I can see that it would be good to have an emergency bypass if you spend time climbing desert mountains, but honestly, at an outside temp of 105º pulling a trailer and fully loaded, I've never had the coolant temp gauge show any increase at all with the automatic thermostat fan switch working just fine after I stop. The moving air seems to cool everything OK, but it does activate if I get stuck in traffic. The OG system seems to work well as far as I can tell. But if you want to do it, tap--this means to splice into or join a new wire into an existing one-- into the red and white wire going into the thermostat and into the red and black wire coming out. However, remember this 12 volts is hot all the time going into the thermostat switch--does not turn off when the ignition switch is off. Thus it you were to pull over and leave the car, you could be running the fan the whole time you were hiking with the risk of depleting the start battery and stranding you in the desert mountain back country. I would only do it with a lighted switch or a separate warning light showing the switch is deployed.

Duncan

Tue May 07, 2019 6:24 pm

Marcq wrote: skills@eurocarsplus wrote: decide what speed you want (hi or low) and tap into that wire

Tap into that wire? What does tap means?

Marc..
"join on to"

Preferably with a proper crimped splice or soldered and heat-shrinked.

Frankly, if you have to ask how to do this, best to find someone who knows exactly how to do it to show you. You do know to disconnect the battery negative first?

Tue May 07, 2019 6:30 pm

stop encouraging this madness, if te stock thermo isnt activated then its not needed. short term solution to a bigger problem if its overheating at lights fix it, dont hack a damn switch in, whats the matter with you?! check the thermostat switch in boiling water, make sure everything is working but dont do a work around to fix the symptom.

Tue May 07, 2019 6:37 pm

Marcq wrote: Phaedrus wrote: You shouldn't be randomly guessing when you feel like overriding the stock cooling system...

Oh no!! Just when I'm stuck in traffic at 100 degrees

At 100°F, your motor is cold. The OG system, if in proper working order, can handle that and more. If your motor isn't boiling over, if the gauge isn't pegged (and you have confidence it isn't lying to you), you don't need to do anything. if you were to run the fan and cool the motor to below optimal temperature, what are you gaining here?

Tue May 07, 2019 7:09 pm

Paulbeard wrote: Marcq wrote: Phaedrus wrote: You shouldn't be randomly guessing when you feel like overriding the stock cooling system...

Oh no!! Just when I'm stuck in traffic at 100 degrees

At 100°F, your motor is cold. The OG system, if in proper working order, can handle that and more. If your motor isn't boiling over, if the gauge isn't pegged (and you have confidence it isn't lying to you), you don't need to do anything. if you were to run the fan and cool the motor to below optimal temperature, what are you gaining here? Agree

Tue May 07, 2019 7:51 pm

Paulbeard wrote:

(and you have confidence it isn't lying to you)

Bingo!! I have a red flashing light going on for apparently no reason(long story)

There's nothing wrong with reinventing the wheel

Marc..

Tue May 07, 2019 8:07 pm

Marcq wrote:

There's nothing wrong with reinventing the wheel

There actually is. And your flashing red light could be a failed relay, nothing to do with the actual temps of your motor. But go on ahead with your plan.

Tue May 07, 2019 8:11 pm

i have a better idea. why dont you just rip the red light out of your instrument cluster?! then, it wont flash anymore.

Tue May 07, 2019 9:32 pm

Is coolant level sufficient. I always thought the red light flashed when low but in one of my vans it would flash if you wiggled the cluster. Turned out to be something with my printed circuit.

Tue May 07, 2019 9:32 pm

Is coolant level sufficient. I always thought the red light flashed when low but in one of my vans it would flash if you wiggled the cluster. Turned out to be something with my printed circuit.

Tue May 07, 2019 9:47 pm

outcaststudios wrote: i have a better idea. why dont you just rip the red light out of your instrument cluster?! then, it wont flash anymore.

That's just crazy. A piece of electrical tape is much easier.

Wed May 08, 2019 6:45 am

Marcq--There is a lot of negativity happening here. It seems to break down into two separate categories which are worth listening to.
1. Why do you feel you need to do this, which implies that you neither trust the original engineering design or don't have enough do-it-yourself skills to understand and insure maintenance to keep the original system working in a way that gives you confidence. (Where does the damn question mark go? In the middle of a sentence --"need to do this?, which implies....", or at the end of a long sentence, which by the time we get to the end of it, we have forgotten that at the beginning there was an implied question?--a little lightness to try to mitigate critical comments.)

2. Apparent lack of electrical knowledge, which implies that if you try to do it yourself, you may very likely compromise the system and cause extensive and expensive damage that will require an expert to repair.

Duncan

Marcq wrote: Phaedrus wrote: You shouldn't be randomly guessing when you feel like overriding the stock cooling system...

Oh no!! Just when I'm stuck in traffic at 100 degrees

Marc..
A perfectly good concern.

At the risk of too much boring information, I'd like to explain a bit about the electrical issues surrounding the fan and its operation. First of all, the fan needs a power source all of the time whether the key is on or not. This was designed so that if the coolant is hot after the car is stopped and turned off, the fan can cool the water in the radiator to prevent overheating and damage to the radiator and adjacent components. That power comes directly from the battery and goes through a fuse bypassing the ignition switch altogether. The ignition switch was designed to handle the loads that need to be active when the car is running, but not any extra; headlights, engine management system, interior electrical needs including the dash instruments and so on. There is not a lot of extra capacity for that switch as Wolfsburg didn't want to spend extra money on every vehicle for the tiny few who wanted to add super powerful driving lights and giant booming sound systems. Failure on 30 year old ignition switches its not uncommon which can result in a stranding.

I would not recommend just by passing the switch because of the possibility of draining the start battery as I mentioned in a previous post.

But here's the rub, you can't simply power the fan by tapping into it's motor with a power source that goes through the ignition and eliminating the battery draining risk by having that go through the ignition switch. This would be a very risky operation that could wind up mixing the two sources and sending power to areas that need to be separate. It can be accomplished by the use of relays that would automatically keep the sources separate. However, you now have an additional complexity that would need to be maintained to insure safety and reliability. That same effort could be put to better use by having a qualified person ensure the reliability of the original well designed system. Even after 30 years, most of us still have reliable working thermostatically controlled radiator fan systems.

Duncan