Volvo fan popping fuses

[Bitch'nBronco]

How do I test a fan motor to tell if it's going bad? I've been running a volvo 740 fan for 6 years with no issues up until recently. I'm using the volvo relay pack and a BMW dual temp switch to trigger the fan. The 30a fuse going to the fan keeps popping at random intervals, I've checked all the wiring and found nothing wrong. I'm beginning to think the fan motor itself is going bad but don't know how to test it. It kind of hard starts (I'll try and get a video in the next few days), not sure how to describe it but it's definitely different from when I first started running this fan.

I may just finally go back to a mechanical fan but need to drive the Bronco a little before my move and want to see if I can troubleshoot it this weekend.

The fan is wired just like the diagram, my switched 12v is off of the ignition.

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[1sicbronconut]

Don't know about the Volvo fans but Ford electric fans draw more than 30 amps to get them starting to run, after they start 30 amps will work fine for the load.

 

[Bitch'nBronco]

I believe that, I just don't understand why after years of running 30A fuse it all of a sudden starts to pop. The wire leading to the fuse was warm the last time the fuse blew. That's why since I checked all my wires and connections that I think its the motor going bad. I just don't know how to test it.

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[nvrstuk]

Put a amp meter on it, read the amperage when it's running. Compare the amperage rating on the side of the Volvo fan to what you recorded.

Without pulling the fan apart to visually check all the wiring, insulation, brgs, etc you can check load.

 

[Broncobowsher]

You might be getting a loose connection causing the load to go up.

I'll agree with others that 30A is a really light fuse for that fan. You got lucky the first few years.

Did you change anything in the airflow? Different radiator, coolers (added or subtracted), bumper, lights, winch, lift, etc? The fan getting more air could let it work harder and pull more.

Any change in electrical? Wiring, alternator, etc?

 

[Bitch'nBronco]

Put a amp meter on it, read the amperage when it's running. Compare the amperage rating on the side of the Volvo fan to what you recorded.

Without pulling the fan apart to visually check all the wiring, insulation, brgs, etc you can check load.

Thank you, will do

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[nvrstuk]

B...Bronco- electrical resistance increases load. You said you checked all connections, etc.

Without knowing what the designed load (amps) of the fan is you have know idea whether you were riding on the upper limit for years with your 30amp fuse and barely gettng by w/o blowing a 30 amp fuse and now with maybe a connection that is less than perfect (exposed to weather, etc, etc) you are just over that fuse limit.

You need to check amperage draw or get an infared "scope" that you can sweep over every inch of wire, every connection and the motor itself to see where if any warmer temps are. Warmer temps (red spots) indicate higher resistance.

I used to do this every couple months where I used to work. From small analog gauges to 200HP electric motors... every connection. Beats shutting pumps/equip down that is designed to run 24/7 and retighten connections when they don't need tightening. You can see the connections that have higher resistance because the infared scope picks it up-then you tighten/clean whatever is needed.

I looked in my old notes and they show the Tauras fan runs on high speed at appr. 35+ amps. Start up is much more.

Here's the only link I saved on the Volvo 240 fan

https://www.240turbo.com/ElectricCoolingFans.html

 

[Bitch'nBronco]

You might be getting a loose connection causing the load to go up.

I'll agree with others that 30A is a really light fuse for that fan. You got lucky the first few years.

Did you change anything in the airflow? Different radiator, coolers (added or subtracted), bumper, lights, winch, lift, etc? The fan getting more air could let it work harder and pull more.

Any change in electrical? Wiring, alternator, etc?

I'll recheck my connections. Nothing has changed with the setup, I did replace my negative battery cable and the fan is grounded to the cable (one of the parts store cables with an extra tie in on the terminal).

I am concerned with stepping the fuse up a size if the power wire to the fuse is getting hot to the touch. If the connections are good I'll try it and make sure I have a fire extinguisher ready haha

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[Broncobowsher]

That new battery ground cable may have been enough to push the fuse over the limit. Seriously that could be what did it. Little less voltage drop through a slightly less than ideal ground. Motor can pull a little harder, over the edge.

What is the relay rated for? Many are only 30A, but there are plenty of bigger 40,50,60,80A relays out there.

Power wire is getting hot? what gauge wire is it? That may be undersized as well.

 

[Bitch'nBronco]

Found a loose connection for the main power wire that I didn't notice the first time thru, hopefully that gets it.

The main power wire is 10ga, I'll redo the grounds just to be sure. I could probably step the main power wire to an 8ga just to be safe, but that's the size from the factory volvo harness which is why I chose to run it. Really appreciate the help!

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[Bitch'nBronco]

Forgot to reply to the relay part, it's a 40A relay

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[blubuckaroo]

What fuse type?
The old glass fuses would have connection issues with higher amperages. They could get hot, from poor connection, and actually melt the element without the amperage being too high.

 

[Bitch'nBronco]

It's one of the green plastic fuses

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[Bitch'nBronco]

That new battery ground cable may have been enough to push the fuse over the limit. Seriously that could be what did it. Little less voltage drop through a slightly less than ideal ground. Motor can pull a little harder, over the edge.

What is the relay rated for? Many are only 30A, but there are plenty of bigger 40,50,60,80A relays out there.

Power wire is getting hot? what gauge wire is it? That may be undersized as well.

Glad it wasn't more complicated than it was, thanks for the help. Turned out it was that loose connection, going to drive a bunch to see if it's been fixed. Thanks for mentioning checking the connections again

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[1sicbronconut]

Ford's favorite term of late is "pin fit issue" getting even more critical with the use of 20-22 gauge wiring and even smaller surface area on the connectors.

 

[Bitch'nBronco]

Ford's favorite term of late is "pin fit issue" getting even more critical with the use of 20-22 gauge wiring and even smaller surface area on the connectors.

I know that pain lol, I wired up heated and cooled seats out of a 2015 f250 lariat in my 01 F250 and fought "pin fit" with those tiny wires. So frustrating

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