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Electric Fan Conversion

The diagram in BDKR's post shows the fan single speed, controlled on-off by a thermostat with a manual overide switch that disables the circuit .

Everything is correct except for the manual override part. The switch that disables/enables the circut is a switched power source! In other words, put your key in and turn to on and the fan circut is enabled.

Additionally, the easy way to run and control your fans is just to get one of these:
flx-31165.jpg


It also has the two stage (variable speed) control you are after.

I decided a long time ago that hacking the OE fan stuff sucks. Here is my fan.
der-16926_w.jpg
 
Alrighty, so I yanked a Lebaron fan today at the jy. In good order. Got it for $15.

What all should I need other than this?

I also picked up a little relay that I found in a Saab 900S there. It's called a cooling fan timing relay. I figured it might be useful. Anyone know anything about it? I'll get a pic here in a bit if need be.
 
Everything is correct except for the manual override part. The switch that disables/enables the circut is a switched power source! In other words, put your key in and turn to on and the fan circut is enabled.

:oops: duh on me, ...you're obviously not using the same (940) relay as Clifford is using. And looking back at the 940 relay, I see now that the fan is "off'" if neither sensor is "on". Which is what I was going for.

Thanks, I think I'm less confused!

Edit: ..and it can also be wired as a Switched power source ?
 
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Check ebay ..."VolvoFan Relay", or post in this forum in 'Wanted' 940/850 efan relay if you want to use Volvo parts.
 
I did an electric fan swap from a 940 into my 1990 740 GLE 16V, using the big radiator, and the stock Volvo relay. This is a very easy swap. The relay has two wires coming out of the middle which are grounds used by the 940 ecu to turn the fan on, one at high speed and one at low speed. I hooked these wires to temp sensors, one in the radiator and one in the lower radiator hose, like a 240 turbo. The low speed wire is on the lower radiator hose. On each sensor, i took the other connector and sent it to ground. Main power wired to the battery+, Done! Now the fan turns on if either sensor reaches it's temp setting and completes the ground circuit.
Much quieter car now- and it runs cooler with the big radiator. Anybody with an engine driven fan should do this swap.

Also put a late 940 intercooler in at the same time. Wonder why?
 
I did an electric fan swap from a 940 into my 1990 740 GLE 16V, using the big radiator, and the stock Volvo relay. This is a very easy swap. The relay has two wires coming out of the middle which are grounds used by the 940 ecu to turn the fan on, one at high speed and one at low speed. I hooked these wires to temp sensors, one in the radiator and one in the lower radiator hose, like a 240 turbo. The low speed wire is on the lower radiator hose. On each sensor, i took the other connector and sent it to ground. Main power wired to the battery+, Done! Now the fan turns on if either sensor reaches it's temp setting and completes the ground circuit.
Much quieter car now- and it runs cooler with the big radiator. Anybody with an engine driven fan should do this swap.

Also put a late 940 intercooler in at the same time. Wonder why?

So, what connections does the 940 fan have? I like how you did it and this is exactly what I've been after, but I have a LeBaron fan that I'm gonna fab to fit. It just has a two prong connection wire coming out of it. Does the 940 fan have some special connections that indicate it's a 2 speed?
 
The 940 relay has power in marked"30" on the relay- this uses a large red power wire in. The output has two poles ,also for power wires. The control part of the relay has two grounds. The relay has two different power paths,each with a different resistance built in, thus one powers the fan with more current at high speed, and the other powers with less current at low speed.
So, essentially there are two relays built into one,plus a resistance in line to control current flow.
The easiest way to do this is to use a 940 or 850 fan relay and harness and just use the grounds to control the relay thru the temp sensors, like I did. (Thanks to 740ATL for suggesting this setup to me).
If you have no Volvo relay, you could duplicate this setup with some simple relays and a couple of resistors with different resistance specs. Add a fusible link rated at 30 amps to the power wire to prevent pyrotechnics!
 
The relay has two different power paths,each with a different resistance built in, thus one powers the fan with more current at high speed, and the other powers with less current at low speed.
I was with you there most of the way. The speed control is built into fan itself not the relay. If you just connect the fan directly to the terminals on a battery without the relay, green wire will give you low speed, red wire high. I have a 940 fan installed in a bmw without the volvo relay and I still have low and high speed functional.
 
Good to know the resistance is in the fan wires, not the relay. Substituting another set of relays would work just fine. Another reason this is so easy. I had a donor 940 and just used the relay and harness when I moved the fan and radiator over. Easily done and a perfect fit w/o mods. Mikey did a similar setup with an aftermarket fan on the cover car and just used a simple relay and radiator temp sensor for a 1-speed fan.
 
Just to add to this thread so I can find it later, lol - on my Volvo relay there were two wires that could be grounded out for hi or lo fan speed, coming right off the relay:

Blue/Black - lo speed
White/Black - hi speed

I used the Saab switch (87/92) in the lower rad hose. Works nice so far.
 
One addition - there is a fan ground wire in the harness, too.
Also-wired my way, the fan will run with the key off until temps cool down.
 
I'm converting my '86 240 to an E-fan, and am also going have another conversion ready for when my '76 244 gets on the road. I picked up 850 fans. I've got one question on it though.

I'm going to set the high speed off an in-line temp sensor (Bottom radiator hose, I'm using a Saab inline sensor housing). I'm going to run this off an ignition-switched relay, so that it only works when the car is on.

The low speed, I'm going to run off of the sensor in the radiator, so it'll continue to cool on the low after the car is turned off.

Does anyone see a problem with this?
 
where do you get the sensors for the coolant lines that turn the fan on at a certain degree (looking for around 190-200F unless someone says otherwise)
i tried an e-fan out of a 95 buick century custom, but the damn fan motor was too big. :grrr:
 
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