radiator fan blowing fuses on high speed - Help please!

[ermie571]

Ok folks,

when I bridge the radiator fan on high speed it pops the fuse.

I was trying to fit a chicken switch.
I cut the wires one at a time...the power to the fan and put one of those wag connectors in
with the wag connectors in, and the fan doing nowt, no fuses blow so I haven't got a dead short there.
Add the cables to the switch, and with the switch off, no blown fuses.
Switch it on, and the fuse blows.

So I stripped out the cables to the switch from the wagg connector and replaced the fuse, all good. No immediate fuses blowing
tested the fan by bridging the connections. All ok at the low speed...but the high speed is blowing the fuse. Immediately.

So - is the fan motor pulling too much and is need of replacement...or have I buggered it.

(although I'm pretty sure its been blowing fuses at high speed previously, - i just hadn't made the connection)

Should add - I'm using a red 16A fuse

any useful tips appreciated


Em

Thinking on this....I suppose I could put the chicken switch on the low speed and run it pretty much constantly....I thought my thermoswitch was buggered...But I guess it was blowing fuses instead calling for the high speed. I'm not sure if I can hear the low speed when the engine is running...

another question...on the two speed switch - is it the low or high speed it calls? I have the wiring for the two speed...but the thermoswitch I took out and replaced some years back has the single setting...Now starting to wonder if the van has only generally called on the low speed.... hmmmmm

[RogerT]

Hi there, I was wondering if that fuse is original ? Looking at the DG wiring diagram you should have a 30A fuse.

http://syncrosport.com/info/wiring/VW_T ... _SP_DG.pdf" onclick="window.open(this.href);return false;

[RogerT]

Ooops, your signature fooled me, you e a DJ. Still 30A

http://syncrosport.com/info/wiring/VW_T ... -92_DJ.pdf" onclick="window.open(this.href);return false;

[jrt]

Our early van(1983) has a 16 amp bullet fuse, as mentioned later vans are higher blade fuses.
David.

[jrt]

We had a problem with the rad fuse blowing and it was caused by a poor/tarnished connection in the fuse box. Cleaned the contacts up and all was good. As for hearing the two stages i can just about hear first stage come on in the cab, second stage sounds like a jet engine.
David.

[syncroandy]

This may help:

[CJH]

If your aim with the chicken switch is to start the high speed fan without going through the low speed setting first, then note that the start-up current can be much higher than the steady-state current, due to the motor having to start the fan turning from rest - typical electric motor characteristic. Admittedly this in-rush current is very brief, and probably doesn't last long enough to blow a fuse, but worth bearing in mind. In normal operation the fan would be running at the low speed before switching to high speed, so the motor wouldn't have to spin up from a standing start. A two stage switch might be kinder on the fuse.

[CovKid]

That or a slow-blow fuse

[ermie571]

Oh god...now I'm very confused...

should it be a 30A fuse...is that what the diagram about is saying?

I can try a larger rated fuse...

and it was originally a DG...then DJ and now AGG

But the fan wiring I guess is 1.9 dg, on the 2 speed setting

regards

Em
x

[937carrera]

A bit of maths helps, lets assume you have the 200 / 300 W motors.

16A x 12.5V (to keep the maths simple) = 200W

A 16A fuse is just enough to operate the fan on slow speed.

300W = 24A @ 12.5, so you need a 30A on blade as stated, or 25A on ceramic / bullet as that I think is the max size

[Oldiebut goodie]

Unless you are in the realms of the 50A fuse which I discovered on the relay by the earth crowns on mine.
Maybe its a 500w one. Easily checked as the relay will be present as above.

[CovKid]

I also discovered (after much trial and error) that blown fuse on high speed can be caused by corroded connections at relay. All I had to do was unseat relay then push it back home again and no more blown fuses. Worth checking that too. The relay isn't easy to find. You need to look just above earth crowns under the dash. You'll see the cables going into the relay socket - it sits on a small bracket.

[937carrera]

..but doesn't the OP need to fit the right sized fuse first

[Oldiebut goodie]

Not for operating the relay, if present. The fan should also have that hefty cable if present.

[bigherb]

You shouldn't need a heavy fuse the chicken switch, which should only switch the relay. It should be connected to the cable that comes from terminal 1 of the thermoswitch.
The terminals are marked on the switch.