Date: Tue, 22 Jan 2008 16:55:21 -0500
Reply-To: Mike <mbucchino@CHARTER.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mike <mbucchino@CHARTER.NET>
Subject: Re: Electrical questions. Radiator fan circuit from 85 Vanagon
into 81 air cooled Westy.
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
When you have poor, corroded wiring/ connections or bad grounding, voltage
drops. When voltage drops, current rises automatically in proportion. This
is due to the current-consuming devices demand on the circuit.
An electric motor normally powered by 12 volts and normally drawing 5 amps
of current flow when running at full speed, will now draw 10 amps of
current, if the input voltage get reduced to 11.0 volts, in an attempt to
continue running at normal speed. The wires get warmer as current flow
exceeds the designed capability of the conductor's diameter.
The factory has designed the wire guage size to allow a small buffer to
allow the fuse to blow due to sudden, severe overload, before the wire would
melt and cause a fire, but not enough to allow for such a constant smaller
overload.
Continuously running the circuit at this higher current flow will heat the
wire warmer than normal, and the wire insulation, plastic plug connectors
and switch bodys will eventually soften and melt from the excessive heat.
For example, the Vanagon headlight switch routes all of the lamp's power
through it (instead of through relays), so as the vehicle ages and the
grounds, etc, become bad, the metal high and low beam contacts inside the
plastic switch housing get hot enough to melt the plastic rocker inside of
the switch, burning it up. When you replace the blown fuse, bad switch, or
melted connector, etc., what have you done to diagnose and fix the actual
problem? Things melt for a reason, not just because they're old and worn
out! The headlight switch doesn't melt because it's old, but because the
connectors and grounds are drawing excessive current. What about those new
higher-wattage headlamps? Are they bigger than the factory lamps? This is
the type of constant overload that melts things.
The Vanagon radiator fan motor, fan temp switch and their plug connectors
sit outside in a sometimes wet, salty, corrosive environment for 15 to 25
years. Even if they were weather-tight when it rolled off the showroom
floor, I bet that's no longer the case. You could take voltage and amperage
measurements at the motor connection (while it's running) to determine
what's really going on there. Measuring closer to the motor is better,
because the voltage will drop a little bit at each connection, and you need
to know what the final figure is getting down to at it's lowest point
farthest along the way, but still before the motor. The brown wires that
return the current path to the ground point could be measured (unplugged
from the motor) separately with an ohm-meter, to determine how much
resistance is present in that portion of the circuit. All of this diagnosis
will tell you where the faults lay, then correct them as necessary to fix
the actual problem, instead of attempting to apply some type of a bandaid to
the problem.
My '87 Westy GL came with a melted headlight switch (anyone have a good one
laying around?), and a bad radiator temp fan switch (no low speed) so I
wired-in a manual fan switch using a vanagon defroster switch in the blank
port on the instrument panel. A curved Exacto scraped off the old defroster
logo to prevent confusion. I like having it for hot days, just in case.
The AC power switch used to do that job for me on my old '84 GL; it had a
bad (removed) AC compressor. so the air never worked while I owned the van.
BTW, there's no need for the led 'ON' indicator, when that fan's on high,
you can't help but hear it, it's loud!
HTH,
Mike B.
----- Original Message -----
From: "neil N" <musomuso@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Tuesday, January 22, 2008 12:14 PM
Subject: Re: Electrical questions. Radiator fan circuit from 85 Vanagon into
81 air cooled Westy.
> Thanks Mark. The help is appreciated, and as a side note, I must say I
> have learned a lot being on this list.
>
> I'll stick with the stock design though I *may* install an LED that
> would indicate when fan is on.
>
> Interesting to note what can happen with over useage of the high speed
> part of the rad fan circuit. When doing electrical work on my Westy
> last year, I was surprised to see one of the heavier gauge female
> spade connectors to one of the fuses was starting to melt. Of course i
> replaced the connector, but you'd think the original design wouldn't
> allow that to happen. Anyway.....
>
> Thanks again. I'll do my best to think things through before posting
> such strange ideas to this list. --- :^)
>
> "Now wheres my drawings for that new oblong wheel I was
> designing....." --- ;^)
>
>
> Neil.
>
> On Jan 22, 2008 6:07 AM, Mark Drillock <mdrillock@cox.net> wrote:
>> Neil, the high speed fan relay is seldom triggered and thus unlikely to
>> fail. On a few vans I have put a manual switch in to activate high speed
>> for special circumstances, using the manual switch to turn on the relay.
>>
>> One thing I would point out is that the older wiring may not really
>> withstand heavy use of high speed and I have seen overheating and
>> melting at the fan fuse holder at S7 on pre 86 models wired to use high
>> speed more often than stock.
>>
>> Mark
>>
>>
>> neil N wrote:
>> > Hi Mark.
>> >
>> > Thanks.
>> >
>> >> Use the relay for sure and make certain to fuse things properly.
>> >
>> > For sure I will. I have the fuse panel and relays from the 85. I was
>> > just "wondering out loud" about making things simpler. --- :^)
>> >
>> > In my rambling thoughts, I figured that relays do fail, so why not
>> > make it so that the only other major part (aside from the fan!) that
>> > could fail would be the thermo switche(s) or fuse. But this thinking
>> > is based on a lack of knowledge. i.e. obviously I don't fully
>> > understand why the relay is in the circuit in the first place.
>> >
>> >>...........
>>
>
>
>
> --
> Neil Nicholson. 1981 Air Cooled Westfalia - "Jaco"
> http://web.mac.com/tubaneil
>
> Engine swap beginings: http://tubaneil.googlepages.com/
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