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  View original topic: Fuses ('81 Diesel)
epowell Fri Jun 07, 2019 7:00 am

HI All

I'm struggling with these old fuses, primarily because they are very hard to find.

All fuses have been behaving well anyway - except one. The fuse for the RAD FAN keeps blowing. I had installed a "chicken switch" (remote manual on/off) for the fan and it was working for a while then started blowing. It is the PINK coloured one which is supposedly 16A. Zoltan is now telling me that probably it should be a 25A or 30A fuse ???

I went to a special shop and they only had 3 fuses: 5A, 16A, & 25A... so I bought 10 pieces of each - seeing as they are only 7 cents each.

I can't seem to find in the Bentley where is lists the ratings for each fuse in the panel > does anyone have handy a list?

In the meantime would it be OK to put a 25A fuse in there for the RAD FAN?

Thanks!
Ed

valvecovergasket Fri Jun 07, 2019 8:00 am

i dont recall a listing for the fuse ratings either, but i was just poking around in there the other night and all of the fuses are definitely in the wiring diagrams.

dont have the bentley handy otherwise id look that one up for you :)

epowell Fri Jun 07, 2019 8:06 am

valvecovergasket wrote: i dont recall a listing for the fuse ratings either, but i was just poking around in there the other night and all of the fuses are definitely in the wiring diagrams.

dont have the bentley handy otherwise id look that one up for you :)

OK... I'll look again at my Bentley but these wiring diagrams kill me!

jlrftype7 Fri Jun 07, 2019 8:36 am

Do you have the earlier 2 speed fan like my '84 WBX, the one with the Low Speed Resistor built into the Fan itself, and High Speed is straight power to the fan? And, which speed is the fan blowing the Fuse at?
Also, which speed did you tap that Switch into for controlling your fan?
Maybe give the fan a spin by hand underneath your Vanagon and see if the bearings are binding. You can also check the wiring for the fan while you're down there. If the diesel model uses a' Hot All The Time/ Power always available in the Circuit' arrangement for its fan like the WBX, disconnect the plug at the fan as a safety measure so it can't turn on while you've got your hand around the fan..... :)

If you can borrow a meter, you can do some electrical tests on the circuit with the fan unplugged like resistance through the windings, then ask others here on whether your findings match their fan motor/circuit.
Make sure your Ground for the Fan is spotless and has no resistance built up from corrosion , I'm betting your ground for the Fan is similar to the WBX's, but your Bentley will tell you for sure.

crazyvwvanman Fri Jun 07, 2019 8:41 am

In my Bentley diagram page 97.40 has the fuse for the rad fan in 82 diesel, 16 amp.

The early wiring and fuse panel is a little weak, I wouldn't risk a 25 amp fuse there. You could easily melt the fuse holder for that fuse. It may already be melted if you look closely.


Mark

epowell Fri Jun 07, 2019 10:30 am

crazyvwvanman wrote: In my Bentley diagram page 97.40 has the fuse for the rad fan in 82 diesel, 16 amp.

The early wiring and fuse panel is a little weak, I wouldn't risk a 25 amp fuse there. You could easily melt the fuse holder for that fuse. It may already be melted if you look closely.


Last Summer afte wiring up the fan myself, including the chicken switch, we set out on our trip and weather was hot so I was flicking the fan on (via the chicken switch) often [kinda overdoing it due to my fascination with the switch]... then one time there was a bit SPARK and pooooof ! > no more fan.

I didn't touch that switch for 10 months... last week I put in a new 16A fuse and while the van's engine was off I tried the ch.switch and sure enough it turned the fan on. I turned the fan off again and started the engine... then turned the ch.switch ON again and "ping", it blew the fuse. It was just a little "ping" this time, now a loud "SPARK" like the first time last Summer. I wouldn't be surprised if that spark damaged something.....???

I think my fan is wired up correctly, and I can live without the chicken switch... I would really like to just have my fan back. I have a new 16A back in there now - and I am guessing I won't know how it will behave in HOT situations until they will happen.


jlrftype7 wrote: Do you have the earlier 2 speed fan like my '84 WBX, the one with the Low Speed Resistor built into the Fan itself, and High Speed is straight power to the fan? And, which speed is the fan blowing the Fuse at?
Also, which speed did you tap that Switch into for controlling your fan?
Maybe give the fan a spin by hand underneath your Vanagon and see if the bearings are binding. You can also check the wiring for the fan while you're down there. If the diesel model uses a' Hot All The Time/ Power always available in the Circuit' arrangement for its fan like the WBX, disconnect the plug at the fan as a safety measure so it can't turn on while you've got your hand around the fan..... :)

If you can borrow a meter, you can do some electrical tests on the circuit with the fan unplugged like resistance through the windings, then ask others here on whether your findings match their fan motor/circuit.
Make sure your Ground for the Fan is spotless and has no resistance built up from corrosion , I'm betting your ground for the Fan is similar to the WBX's, but your Bentley will tell you for sure.

Honestly I am not really sure what type of fan mine is... all I know is that the HIGH SPEED wire is the thin wire. I was told that this is because that thin wire simply goes to a relay. Otherwise the LOW SPEED wire, which is thick, goes directly to the fan.

I think I wired my chicken switch up to the high speed (now 100% sure however).

Paulbeard Fri Jun 07, 2019 10:36 am

I think you may want to rethink the chicken switch. My experiences are revealing that underneath any Band-Aids™© we add is a Real Problem we need to fix. In most cases, stock/OG is good enough and where it isn't, it would be best to make a real improvement (larger/better wiring, etc.) instead of cutting in something that doesn't address the problem.

epowell Fri Jun 07, 2019 10:51 am

Paulbeard wrote: I think you may want to rethink the chicken switch. My experiences are revealing that underneath any Band-Aids™© we add is a Real Problem we need to fix. In most cases, stock/OG is good enough and where it isn't, it would be best to make a real improvement (larger/better wiring, etc.) instead of cutting in something that doesn't address the problem.

Actually the fan was kicking in properly without the Ch.switch. Probably should never have added it.
I certainly won't touch it anymore, and I guess just hope, for now, everything will work normally. We leave on Monday for our trip so not time now to dig into a big wiring project....

PS - although I probably could make time for removing the ch.switch. hmmmm.... maybe I should do that?

Paulbeard Fri Jun 07, 2019 10:56 am

epowell wrote:
PS - although I probably could make time for removing the ch.switch. hmmmm.... maybe I should do that?

I think it would be a good idea if you can verify that all the stock wiring is good.

crazyvwvanman Fri Jun 07, 2019 11:01 am

In normal operation the fan will be running first at lower speed, then when the rad temp switch tells it to go to high it simply speeds up. By going straight to high speed with the manual switch you are kicking the fan motor into high from a dead stop. That wouldn't happen in normal operation.

Motors have a characteristic that they pull higher amps while starting up than they do running normally. The low speed startup is likely at a lower amperage than your straight to high speed forced start is.

When driving down the road the fan is probably turning just from the air flow through it so your manually turning on high speed may not require as abrupt of a motor start as when parked and you turn on the switch.

The above is just to help explain why the fuse only sometimes blows when you use the switch. Lots of other people use such a switch without problem. Also, a standard test is jumpering the various speeds at the temp switch connector and again people do that all the time without blowing the fuse. So it indicates some marginal condition in your van that results in blowing the fuse when it really shouldn't blow. It may be a combination of small things. I would definitely fix this. For long term ownership I'd try to improve things with a little extra work.

Mark

epowell Fri Jun 07, 2019 12:57 pm

Thanks guys for the input. Mark, that explains a lot about the blowing!

So, just when I was thinking that I was really getting on top of my van > I am now reminded of the biggest remaining vulnerability > wiring! Expecially under the dash.

I think now is too late to dig into this wiring, since we leave on Monday - let's hope a wiring issue doesn't break us down on the road. Now I have my next major project outlined for myself: DASH REMOVAL and dealing with everything back there including all wiring.



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