Rad Fan Test

[MadBeez]

I think I have a dead radiator fan. I sent the radiator out to be tested and or repaired and removed the fan and shroud per their request. I have no idea whether this fan worked when I first acquired the car so I decided to test it and then clean it up if it was good.
There is just one connector with two wires in it going to the fan. According to the wiring diagram there should be a black wire with power and the housing should be the ground. I assume that the blue wire completes the circuit through the fan switch.

So I tested the battery from the FIAT that's been on charge and it tested good. Then using some alligator clips I put the negative pole to a bare stud on the shroud and the positive on first the black wire and then then the blue wire - nothing. If the fan motor is good I would have expected it to start right up.

Am I doing this right?

https://drive.google.com/file/d/1x2-u3o ... sp=sharing

[ORFORD2004]

Yes dead motor if you reverse the wire in DC the motor will spin the other side.

[scrapironchef]

The fan doesn't ground through the housing, it grounds through the thermoswitch in the radiator. Apply +/- through the two wires before you give up on it.

[MadBeez]

Looks like it's dead, dead. I opened it up though and it looks clean inside - no signs of arcing, wires good, no cracked insulation. The magnets are clean, windings look good. Can't see why it wouldn't work.

Anybody have one they want to sell?

Thanks, Rich

[Nut124]

I just threw one in recycling two weeks ago.

To test you must connect both wires. Black to ground, LTBLU to +12V.

In the car, the LTBLU should always be hot when ignition is on. The temps switch is in the black wire and closes when hot allowing ground.

[MadBeez]

I should've said that I did try + and - across the two wires but nothing there either. Then, after cleaning out a little dust and putting it back together, I tested with an Ohm meter and found no short to the case from either wire and about 2 Ohms across the wires. When I slowly rotate the shaft, I get a jump to like 18 - 22 Ohms and then back to 1.5 - 2 Ohms. Oh, and still didn't try to spin when 12 volts was applied.

Just doesn't make sense that it won't spin or even budge - it rotates freely by hand.

~Rich

[MadBeez]

Has anyone tried one of these from Vick's: https://www.vickauto.com/FIAT-PARTS/FIA ... KU-11-3390

Thanks, Rich.

[18Fiatsandcounting]

Rich, I have not tried the Vick's fan so I'm not much help there. However, it doesn't sound like your current fan is totally dead if you measure 2 ohms across the two leads. Since Voltage = Current times Resistance, that would mean 12 volts = 6 amps times 2 ohms, and 6 amps is about what these fans draw when they are working.

However, since your resistance measurement jumps around, my guess is that you have bad brushes inside the motor. These are the blocks of carbon that electrically connect to the center of the motor, and they do go bad.

As you can probably tell, I'm not ready to give up on this fan yet. If you haven't done this, try connecting the plus and minus to the two leads inside the plastic connector, and try pushing the fan blades around to "help it get started". For safety reasons, I would NOT use your fingers just in case it does jump to life, but use something fairly soft and flexible like a thick plastic straw or tube. That should be strong enough to push on the blades enough to see if it starts to turn on its own.

If still nothing happens, you can take the motor apart the clean up the brushes, but this may be beyond the level of effort that you're willing to go to. Your call on that one. And, if the brushes are totally shot, then you're back to getting a new fan anyway as brushes are hard to find for this motor.

I'd also be really sure that your battery is able to supply 6 amps. Some old batteries appear just fine when there's no load on them, but if you put any significant load on them, the voltage drops way down.

-Bryan

[spider2081]

When I slowly rotate the shaft, I get a jump to like 18 - 22 Ohms and then back to 1.5 - 2 Ohms.

I think Bryan has a good point.

My first thought is did you ever see the fan run?
I agree measuring resistance between the the black and lt blue wire should indicate something should happen if connected to a voltage source.
It been a long time since I bench tested a coolant fan. I think with the fan blades off the motor, the motor drew less than 5 amps when running. With the fan blade installed the current increased to around 10 amps. I also think the start -up current for the motor with the fan blade installed would be over 20 amps but that would be very short duration. So short that the 16 fuse does not fail.
The fact that the resistance changes when you rotate the motor shaft indicates the current path through the brushes and armature is intact.
It would be interesting if you could measure the voltage across the blue and black wire while they are connected to the voltage source.

[MadBeez]

Thanks Bryan, I did all of that, including giving the fan a push with my finger. Took it all apart too but didn't find anything unusual inside that would keep it from running. I would expect it to jiggle a little when I applied power, but nothing. Think I'll try my battery charger as a power source and see what happens.

UPS just showed up with my valve shims so I might switch back over to that.

~Rich

[MadBeez]

I'll rig up some leads with some female fastons and make the 12 v connection away from the connector so that I can read the voltage when they're coonnected.

I have not ever seen the fan work - lots of over-heating on the attempted drive home from the sale - so a pretty good chance the fan wasn't working then either.

~Rich

[MadBeez]

Well I'll be damn3d - nothing with the charged-supposedly-good battery but, works great with my battery charger as a power source. Close all open browser tabs concerning replacement fans and thanks to all of you for your suggestions.

~Rich

[18Fiatsandcounting]

I'm glad you found the issue before tossing the fan, Rich! Yes, I've had some batteries that seemed just fine when I'd measure the voltage with no load, including when running relatively low amp things like a tail light or such. However, once I tried to draw more than a few amps from the battery, it just laughed at me.

-Bryan

[dinghyguy]

Maybe connect it to the battery of another car just to be sure. Then you will know if you have another project to clean it up and paint it. One thing to check is to make sure the connectors are clean and there are no breaks in the wire, may be some gentle bending of the wires when the fan is running to confirm all seems good.

cheers
dinghyguy

[MadBeez]

Think I'll try that D-guy.