Thanks for posting that. I read about that switch on another write-up. It would certainly simplify the wiring. I could pull a couple from the j/y and keep a spare in the glove box.

http://www.rx7club.com/showthread.php?t=839089

 

That is the worst diagram I have ever seen and I'll leave it at that.

Josh

 

How does that help anyone? Some of us out here are electronically UN-inclined and are looking to learn. How about you explain why...?

 

X2! kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk

 

I really like that guys idea and write-up, but the Mark VIII pulls a buttload of amps for 2nd speed. I tried a normal Bosch relay and just playing around in the driveway it fired within seconds. A Ford diesel glow plug relay fried within minutes. That's why had to install a 200+ amp continuous duty relay.

So I question whether the Volvo unit can handle the fan on high speed.

Josh

 

And the Taurus and Mk8 use the same motor, iirc. Dcc and Hollister road use 70 amp relays for the high sp. And that is covering for initial spike. Normal draw is 30 amps on high. Are you starting directly on high? That is supposed to spike higher than going from low to high.

Dude, that is a bigger amp rating than the fuse on the main power line on a 130 amp alternator! Have you considered that maybe your motor is drawing so much because it's at the end of its life?

 

There is soooooo much wrong where to begin?

On the 1st Relay the led is ON when the toggle switch is OFF, ummm ok.

On the 2nd relay, the temp switch is doing what? Nothing, unless there is + going to it, or it needs to be ran as the ground on 86.

The "probe" engages Hi speed which seems counter productive, if anything the LOW speed should be temp controlled and HIGH speed should be manual.

Also, HIGH speed is going to blow those relays in no time.

The key is finding a dual temp sending unit that has the on-off qualities you desire. Then use that to trigger each respective relay.

So say 195 on 185 off and 220 on 200 off should be safe to keep the high speed and low speed seperate.

Josh

 

Keep in mind I use a 60 amp fuse for HIGH speed. The simple Bosch relays cannot handle it, whether running the fan on LOW and kicking HI or starting on HI immediately. The 200 (I think it might be 250) continuous duty relay was for peace of mind and overkill.

For main FUSE on the alternator I run a 175 megafuse.



Josh

 

I'm not a fan of the diagram in question either. If I'm not mistaken it shows the fan on low as long as the ignition is on. That seems pointless or lazy to me and there's no way I would run that kind of power through those relays. Josh is absolutely right to use a heavy solenoid to switch the fan on.

So anyway, I picked up two of these and two 3G's today.

<a href="http://s742.photobucket.com/albums/xx65/Fordworth/Electric%20fan/?action=view&amp;current=IMG_20110201_164645.jpg" target="_blank"><img src="http://i742.photobucket.com/albums/xx65/Fordworth/Electric%20fan/IMG_20110201_164645.jpg" border="0" alt="T-bird fan"></a>

I talked to my parts guy and he suggested using two generic thermo switches of different temps to trigger the relays. Cole/Hersee has lots of them in their marine catalog for triggering lights and alarms on boats. These would make the wiring clean and simple since you could keep all the hot wires near the relays close to the power source and to run two ground wires over to the switches on the engine.

 

I used standard bosch 40 amp relays with a 35 amp fuse and they work fine with a taurus fan. Cools a 78 built 400.

If you use the jetta temp switch, that I posted, it energized both high and low when its warmed up, you just need to make sure you wire the second relay to deenergize low when it calls for high speed. I can't post pics with my account or I would post a diagram. It's really simple with standard relays SPDT relays. Total cost about $60 including the fan.

 

What are the temp levels on the VW switch?

 

its 88 C and 93 C

or 190 F low and 199 F high. I posted 185 and 190 earlier in the thread, but that wasn't correct.

I have one main fused wire going to the first relay, going to the normally open switch. when low is energized it closes the first relay sending power to the normally closed side of the second relay powering low speed. When the temp switch energizes high, it switches the second relay diverting power from low to high. So when it calls for low speed only the first relay is energized, when it calls for high speed both relays are energized. It's only sending power to the motor on one speed or the other, not both.

The temp switch is wired through ground to control the relays.

Does this make sense?

 

I like the 88 Jetta switch, but there is overlap with the high turning off and the low turning on. A little light in spread as well now that I look at it. The newer Jetta are running too cold.

215 ON 188 OFF

203 ON 185 OFF

Josh

 

I'm not sure what you mean by overlap? When engine temp reaches 190, low comes on, when it reaches 199 high comes on and stays on until engine temp comes back down to 190.

It works awesome for me.

 

The 2000 Caddy Catera looks promising with two sensors...

212 ON, 203 OFF

230 ON 217 OFF

Have to figure a way to shut off relay 1 when relay 2 is active.

Josh