71 sb backseat booster fan help

[joeypregont]

so my heater cranks pretty damn well, but i realized last winter that it wasnt enough for this colorado weather. i do have an inline booster under my backseat that wasnt hooked up. there are two wires coming off of it, so i guess it just has one speed, not sure if its stock or not. i hooked it up to a ground for a fuse thats already under the back seat and jumped the other wire straight to the battery and it fired right up so i know it works.

my question is this-
in order to have it operating on a switch (which i assume is the fan looking switch on my dashboard... correct me if im wrong) i need to draw power from the batter, to the switch, from the switch to the fan... anyone have some basic directions to doing so? where is my power to the switch coming from? and what are the leads on the dashboard fan switch?

edit: any pictures of your functional booster fan wiring would be great, please dont post a wiring diagram for me i've already been searching and looking at them and they quickly turn my brain to mush.

thankyou
joey

[yellrhd]

Show us a pick of what you have.
There were never any factory installed boosters so the switch your referring to may in fact run your fresh air fan / defrost.

Not knowing the amperage of the fan motor the best way is to wire it using a relay and a switch. Use the switch to trigger the relay making sure the switch draws power only when the key is on and the relay will supply the fan with power.

[Tim Donahoe]

Since you already have an aftermarket booster fan under the rear seat, perhaps the previous owner who installed it, also installed some kind of switch for it in--or under--your dashboard.

Were there any loose wires nearby the ones you temporarily hooked up to test the fan unit?

What does this/these fan(s) unit(s) look like? Is it some in-line arrangement integral with the heater tubes under your back seat?

I'm assuming you have two fans under there: one for each heater tube.

The previous owner may have hooked up the fans and not completed the job, by wiring in a harness, connected to a switch near or on your dashboard. He may have set up the rear-defroster relay to actuate the fans. But if he did, then the fans may have pulled more than the 8 amp in-line fuse to that defroster relay.

So take a few clear pictures and show us what you have.

Tim

[joeypregont]

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This is what I have for pics, not at home with the car right now will post up better pics when home if need be

edit: just hopped on the work computer rather than my phone to check the pics and realized there are pretty much garbage pics... i'll take some good pictures tonight to include the fuse that is also near the fan and some kind of relay it looks like.. I just don't know.

I do, however, have a red switch on my dash that is a up and down flipper similar to a light switch that is unused. I did look at the back side of it under my hood and it has 3 stake ons, so I would guess power to the switch, power from switch to fan, and a ground perhaps? will get better pictures up tonight to include the switch front and back and larger fan pictures that show the fuse and relay.
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71 super beetle daily

[joeypregont]

So here are the other wires near my booster fan. All of the stake ons on this fuse and relay( or whatever they are) are full, and all of the wires besides the two from the booster fan are going somewhere so i dont think that they are wired up for below the seat currently...

I used the ground screw on the left side of the fuse box above the booster in this picture when i jumped it, and sent the wire nut'd wire over to the battery and it fire right up

side view here.. all stake ons are used

here is the switch i plan on using if it is possible... bottom left red one.

here is the same switch on the back side under the hood. wide open stake ons..

i dont know what this switch is supposed to be for but i figure it can be used for whatever i want it to be feel free to let me know if im wrong.
and a response to the earlier question, i dont have a fan on the passenger side. there is a tee in there with some insulation around it


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71 super beetle daily

[DeathTrap]

[joeypregont]

I'm not opposed to doing that. But my rear defrosters are not hooked up either and I don't know what to do for that route of wiring... Is the defroster one of the leads coming off that power block looking deal in my picture? I'd still have to run power to a switch at my dash and back to the fan though somehow..
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71 super beetle daily

[Tim Donahoe]

You have a stock in-line VW 8 amp fuse holder in one of your pictures. This fuse holder is for your rear window defroster.

One wire, attached to the fuse holder will go to a small silver relay that's in the same well as your aux. fan. One of the wires coming off this relay supplies power to your window grid.

Turn on your defroster switch and see if you get power to the output of the in-line fuseholder (the 8amp fuse may have to be replaced with a new one for this test). Then check the relay for power output.

The larger silver box with all the wires is just a voltage regulator. The smaller silver box toward the bottom of the well is the relay for the rear window defroster (which may be a suitable power source since your window grid is probably shot, anyway).

Although, if you decide to run wires from that empty switch up on your dash, make sure you provide an in-line fuse.

Tim

[joeypregont]

[Tim Donahoe]

Well, mine is on the dash to the right of the steering wheel. Yours may be under the dash--a kind of toggle switch. Do you have the Owner's Manual? Look in there, or go to the Technical section on this page (in the menu) to look up your Owner's Manual. Look for the switch location in there.

Don't leave the switch on for too long--just in case it actually makes something work .

To be honest, I'd route a new wire to the fan. God knows how many amps that sucker will take.

You realize that if you have a good, working engine thermostat and flaps, you don't actually need an auxillary fan?

Tim

[joeypregont]

[Tim Donahoe]

Without the thermostat/flaps system, your engine would take a long, long time to heat up and give you warm air to the cabin--especially with temperatures like you mentioned.

Also, you want warm air for clearing your windshield.

My defrost button is between the two red buttons.

Tim

[joeypregont]

[joeypregont]

so.
i cannot locate a switch for my rear window defroster, but after a second look i located the wire going from the small silver relay under my back seat to my speedo... and the wire from the relay too the window is also there. i cant find a switch that it should have belonged to anywhere. the window had to have been hooked up to a switch?? yes?? does anybody know where that switch is supposed to be.. what other wires should i have for the rear defroster? i want to hook my booster fan to the rear window grid....
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71 super beetle daily

[Tim Donahoe]

Joey, go to the "Technical" section (the tool bar is at the top of this thread).

Get the owner's manual for your year.

Tim

[Tim Donahoe]

I just went there to your year's Owner's Manual.

Number 18 in the pic I clicked is for the rear defroster button.

It appears to be just to the left of the steering column and under the dash.

Tim

[mikeonthebike]

My 72 SB and I believe 71s also have the rear defroster switch under the dash right before the fuse box.

[joeypregont]