Date:         Sun, 25 Apr 2010 11:36:03 -0700
Reply-To:     Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject:      Re: PWM controller ,
              was Water Cooler System Design Flaw Workaround?
Comments: To: Tom Hargrave <thargrav@HIWAAY.NET>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
              reply-type=original

I don't know who 'they' in the first line are,
but vanagons use radiator coolant temp to control the rad fan, not engine
coolant temp.

and ....a manual control switch would be one way to get that 'head start'
you speak of, as on a hill.
But I wouldn't turn on the rad fan at any reasonable road speed.

I like hearing the rad fan come on automatically ...
it's nice to know that system is working.

I also like to see a vanagon be able to just sit idling on a war day, and
the rad fan cycle off and on. As a test of the whole system.
That tells you a lot of good things about the cooling system.
If it'll do that .....fan comes on for a minute or so, shuts off, comes on
again in a couple of minutes, then shuts off etc..
and it will do that until it runs out of gas ...like 'indefinitely.
that pretty much tells you the whole cooling system is working as it should.
Pretty much anyway.

Scott
----- Original Message -----
From: "Tom Hargrave" <thargrav@HIWAAY.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, April 25, 2010 9:06 AM
Subject: Re: PWM controller , was Water Cooler System Design Flaw
Workaround?


>I just found the schematic on line and they are already using engine
> temperature to control the fan. I thought they would since VW is a
> excellent
> company.
>
> This being the case, something may be worth designing that turned on the
> fan
> earlier based on temperature change, like for example when pulling a hill,
> to give the cooling system a jump start on cooling.
>
> Tom
> www.towercooler.com
>
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf Of
> Mike "Rocket J Squirrel"
> Sent: Sunday, April 25, 2010 10:18 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: PWM controller , was Water Cooler System Design Flaw
> Workaround?
>
> Alistair Bell wrote:
>> my rad fan is 450 W if that helps
>>
>> alistair
>>
>> PS i dont see the point in a pwm controlled fan, I would concentrate
>> in a more sophisticated temperature interpretation, ie a PID
>> controller... monitor rate of temp change to that fan can keep on top
>> of things...
>>
>> but you know, my experience of the fans in real life is that they come
>> on, cool the van down and go off.... seem to work fine :)
>
> I'm with the Bell on this one. The radiator on the fan is capable of
> creating lots of cool water, and the thermostat opens and closes as needed
> to draw from that reservoir. If the engine was seeing huge over and
> undershoots in temperature then a better control system would be
> warranted.
> But the large thermal mass of the engine pretty much assures that temp
> changes will occur pretty slowly, and the thermostat seems capable of
> keeping up with them.
>
> I guess I don't see a problem that needs solving. But I do enjoy fancy
> engineering for engineering's sake, too.
>
>
> --
> Mike "Rocket J Squirrel" Elliott
> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
> 74 Westrailia: (Ladybug Trailer company, San Juan Capistrano, Calif.)
> Bend,
> OR KG6RCR