Parasitic drain and weird relay issue

[woteva]

You still have the old style fan resistor with the metal cage ?
I have seen the coils break and part of it might be touching the cage and causing your current draw ?

 

[shadetreemechanic]

Yeah I have the old style cage one, had a close look and one coil is pretty close but not actually touching the cage. Can clearly see a break in the middle size coil that accounts for speeds 1&2 not working (smallest coil wired in series with middle coil, so middle by itself is speed 1 and middle+small is speed 2).

Let's assume for a sec the coil is shorting to the cage, would that cause the current draw even with the fan selector at the off position and iginition switched off?

 

[woteva]

Let's assume for a sec the coil is shorting to the cage, would that cause the current draw even with the fan selector at the off position and iginition switched off?

Not sure, but does it still draw power with it removed ?
If there are lose bits inside the cage, they may not touch after you have removed it ?
I do remember the cage is connected to the vehicle body through the mounting bolts.

 

[shadetreemechanic]

I have to test it tomorrow when I fix up my multimeter.
Had another look at it just now, the mounting bolts only go thru the plastic moulding so the cage is likely to be isolated in this case *shrug*

Edit: actually it's hard to be sure if the cage doesn't contact the metal vehicle body, like you said it probably does.

 

[shadetreemechanic]

Ok well...no luck. Just got the multimeter going, tested with the fan resistor out of the car and yup the drain's still there 160mA and I can hear the blower relay click on as soon as the battery is hooked up.

 

[Immortality]

The relay is switched by the fan switch. disconnect the fan switch and test again.

 

[shadetreemechanic]

Yeah that was the last thing I could think of....aand nope.
Yanked out the fan switch control unit out of the car and still the relay engages and the drain is present. I'm stumped

 

[shadetreemechanic]

Alright so I figured out it's the relays themselves that cause the parasitic drain. I now have two of them one Narva, newly replaced during the melted fuse incident a few months back and a Bosch that's brand new as of yesterday. They've now both been in the blower relay socket and they both behave the same.

Remember how I mentioned the new Bosch relay appeared to fix the drain for a few seconds, it then clicked and must've broken inside so the blower socket is killing them somehow.

I just tested both of them in the ignition relay socket (old Bosch ignition relay that's normally there works fine - no drain) and no relay plugged in the blower socket and the drain is showing 160mA with either of the Narva or new Bosch relay. Jam the old Bosch ignition relay back in and drain is gone.

Anyone come across this kind of thing before?

Edit: Also the blown 10A fuse in the multimeter when bridging the blower relay coil connectors...I wonder what kind of amperage is running across that circuit? Seems to be what's busted up these 2 relays internally, but funnily enough they still actually work and operate the blower just fine. Weird.

 

[Lex]

I've read similar stuff before in old threads. I forgot about them.
I also didn't think this thread was going down the same path.

Where are you getting your relays from?

 

[shadetreemechanic]

Well the Narva was from Repco it's a 5-pin 30A rating Made in EU.
The new Bosch was from Auto One and it's a 4-pin 40A rating (they didn't have 30A ones except Narva brand and at the time I blamed the quality since Narva have repeatedly let me down in the past - with light bulbs not relays lol) and it's Made in Portugal.