In my previous posting I told of my experience of a fire on my 91 740 Turbo which, I thought, was caused by deteriorated insulation in the wiring harness. The insurance appraiser and the repair shop determined that it was started by a short circuit in the electric cooling fan which caused the wiring to overheat. It damaged the harness all the way back to the fan relay and the relay itself. According to the wiring diagram, it appears as though the control side of the relay is fused but the power side is not. And there is a direct line from the battery to the relay. This line is part of the harness (part way along at least). It's obvious that a short in the fan wiring could melt the harness so that a direct short from the battery to ground through this wiring can cause a fire like I experienced. To stop the short, I had to disconnect the battery, it wasn't good enough to turn off the ignition key. Maybe it would be a good idea, as Steve suggested, that a fusible link or fuse should be in the power side of the relay. Anyway, I'm glad it wasn't a problem with old and brittle wiring insulation because all of us with older Volvos have a lot of miles of wiring in these things.
Thanks to everyone who offered advice. You guys are great.
Dennis

Can someone with a DC ammeter check the current draw at startup and in operation of the electric cooling fan on a 940? This will help in designing a circuit protection device.

OK guys,how do we design this? I like the idea of a fusible link in the circuit: fuses can corrode. Amperage?

Steve - I kinda lied in my post below (like sorta pregnant) - I didn't literally install a fuse. I used a 30A Shortstop (brand) thermal breaker...the nice thing it has plated, threaded terminals for ring terminals so corrosion has not been a problem in the past 5+ years. Available at Speedshops or places that carry the "Painless wiring" stuff.
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www.fidalgo.net/~brook4

Pablo: why 30amp? Did you test startup current draw?

But I like the breaker idea.

First I have zero idea what the stock pusher fan (ac condenser) fan draws.

My fan draws in the teens as I recall. I did not measure start-up, but I bet this type of motor doesn't have a huge delta @ start.

20A by my wild-ass guess would have been too close - 30A will still protect against gross malfeasance and still keep the smoke in.
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www.fidalgo.net/~brook4

I like your Shortstop idea: I found the Bussman catalog page and it's a nice solution. Where did you mount it?

This is on my 245Ti. On the sheet metal in front of the battery next to the oil cooler. Two sheet metal screws. Piece of cake. (I guess this is another benefit)
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http://www.fidalgo.net/~brook4/oilslubesfilters.html

Thanks for the update.

I have a fuse on the high side of my electric fan conversion....I guess Volvo saved $1 on yours....
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www.fidalgo.net/~brook4