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Old 06-10-2018, 10:21 PM   #1
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Join Date: Nov 2017
Location: Houston
Default speed switch at certain speeds, any recommendations 1990 volvo 240 auto

I'm looking for something that will give me a 12vdc signal plus or negative when I hit 40 mph or so. I'm going to have it turn off my AC fan. It is a pretty powerful fan and I'd like to turn it off if I'm at speed.

I found this https://www.lingenfelter.com/product/L460340004.html

But I'm curious if someone has something else.
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Old 06-12-2018, 09:47 AM   #2
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That switch seems to just buddy up to the current speed sensor on the car, but I wonder how it's converting it?

This all said, doesn't LH2.4 have this function but based on temp? I wonder if any of the tuning people could make an adjustment for it to work the way you'd want?
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Old 06-12-2018, 11:37 AM   #3
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JEGS and some other sell different versions of driveshaft rotation speed sensor (usually Hall type). You'll still have to design circuit to convert that to the relay control signal.
This can also be useful for electric intercooler fan control on turbos- not just AC.
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Old 06-12-2018, 11:49 AM   #4
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Location: S NJ, a suburb of Phila.

If a 1990 240 has a factory pusher fan it is usually triggered by a temp switch either in the lower coolant hose or the radiator. That wouldn't let the fan come on if you are driving at 40mph since you should have enough cooling at that speed.
1982 242 turbo. 340k miles. Good stuff and lots of rust.
1993 245 Classic, 420k miles, enem V15. IPD bars and chassis braces. Simons sport exhaust from Scandix. sbabbs ezk chip. Been a good road warrior. Genuine Volvo rebuilt leaky M47.
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Old 06-12-2018, 11:56 AM   #5
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I was assuming he meant with the A/C on.

I think my '93 240 would only turn the fan on if a high-pressure switch in the A?C system kicked on, meaning the condenser was getting a little too warm and overpressuring the system. So it would kick off if it was getting sufficient airflow, regardless of speed or air temp.

I guess that's another alternative, they certainly sell adjustable temperature switched with probes designed to fit into radiator fins, you could get similar functionality, just more directly aimed at the issue - how warm the condenser is.
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Old 06-15-2018, 09:43 AM   #6
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I thought about the temperature switch but I never liked the adjustable probes in radiators. I figured someone made a nice little gps unit that would go in easily.
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Old 06-15-2018, 12:52 PM   #7
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Sure, but it's going to cost you ten times or more what a temp probe and a couple of relays would.
'87 240 budget wagon.
Originally Posted by Dirty Rick View Post
Navigating the Siskiyous in a 3 wheeled Volvo will not end well.
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