blower motor resistor faulty

[modustollens]

The cab heater fan is only running on high speed. I removed the blower motor resistor:

http://www.nissanpatrol.com.au/forums/images/imported/2015/10/95.jpg (http://postimg.org/image/ars34jrvr/)


It is obviously faulty. There is a small piece of metal that attaches to the left metal bracket that the coiled metal is attached to (here is a larger image: http://postimg.org/image/nbf1enbcb/).

The fan will work on all speeds when this little metal pin is touching the left coil's mount; but the coiled wire gets pretty hot when it is running. There is continuity between all the terminals only when this pin is touching the left coil's mount.

I assume this now-detached metal pin is some sort of safety device designed to stop power from flowing if the resistor coils are getting too hot - it looks like the solder attaching the pin to the coil mount loosened.

I am not in a place where I can easily get another one of these parts. I looked around the junk piles but could not find one that is an exact match and I am now left with two options:

(1) buy some old random one and make patching wires to join my truck's harness to the random resistor I find in the junk shop; or, (2) replace the resistors on the one I have (I know a shop where I can buy resistors - i just hope, once I do the math, I can find the right size).

Or, should I just try and solder the pin back on? Perhaps the resistors are fine and it is only the pin that has come loose? But how would I know if this is so? Of course, the coils did get pretty hot when I manually attached the pin - hot enough to make paper smoke!

Anyone know off hand just what size each of these resistors are?

I pulled the fan cover off and saw '12 volt' written; but I did not see any amperage written on the fan; the fuse for this circuit in my patrol takes a 25 amp fuse.

Has any tried either of these strategies with any luck?


Thanks,

MT

[Yendor]

It's normal for the resistor to get hot when in use. They need the air from the interior fan to help cool them. You shouldn't run the interior fan when the resistor is not mounted in the ducting.

I would just try and rejoin the pin back on.

Make sure the interior fan is spinning freely. If it's binding this can cause resistors to burn out.

[modustollens]

Yes, I understand. I know resistors will get hot; but this one was getting super hot. How hot is too hot? I really don't know.

So, you don't think the pin coming off is designed to work akin to a fuse?

I'll rejoin the pin via some solder and see what happens...

Thanks for the advice - this is a lot simpler than what I was initially thinking.

MT

[Yendor]

If the interior fan is drawing to much current this will make the resistor get hotter. They do get very hot in normal operation. Check the interior fan motor.

[modustollens]

Ok; I'll hook the multi-meter up and see how many amps it is drawing... It was squealing a bit before and I put some light oil on it. It is super old and could likely use a good cleaning too.

MT

[modustollens]

The pin soldered back in place easily enough

http://www.nissanpatrol.com.au/forums/images/imported/2015/10/103.jpg (http://postimg.org/image/whx59vnyh/)

I'll see if it lasts or if the resistor is getting so hot it will melt again. Or start the car on fire ;).

Thanks,

MT

[Yendor]

So.......how did it go?

Is you vehicle 12 or 24 volt?

[modustollens]

All is well. Out on the steppe now setting up camp and the HF. So far fan is working normally, just as it was before. No fire yet...

MT

[Yendor]

Cool......just have the marshmallows ready :)

[modustollens]

No marshmallows needed - all is going well so far though some idiot did back into the truck on Sunday and bet the hell out of the bumper and broke a lamp. But there are no shortage of idiot drivers everywhere.

A shot of my camp from last week:

http://www.nissanpatrol.com.au/forums/images/imported/2015/10/154.jpg (http://postimg.org/image/ysvwd1nd1/)


MT