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Discussion Starter #1
I have my heater relay for my 220V pack grounded on one 12v side and
the other going to the positive wire of my heater fan through a
switch in the dash which used to be the AC switch, When the AC switch
is on and the fan is turned on the relay makes contact on the first,
second and third fan speed position but on the fourth position or the
highest, the relay drops out and I need to turn the fan off to get it
to contact again. I have a diode across the relay coil (not sure if
needed) and that's it. Any suggestions as to a fix for this and why
it happens on the high fan speed setting?

Thanks,

Mark
 

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Discussion Starter #2
HI, Mark

I've set up my Echo the same way ( using the AC switch to control the
heater) so I'm familiar with the wiring.

The fan takes a lot of current on high (about 12 amps) , so I can think of
two possibilities:


1. Your 12V system voltage is dropping enough to drop the relay out. Put a
voltmeter on your 12V system and watch the voltage as you change the fan
speed.

2. There is enough voltage drop in the AC switch or wiring to allow the
relay voltage to drop when the fan is on high.

To check this, put a voltmeter on the relay coil and watch as you change
fan speeds.

What relay are you using?? It could be that the AC switch itself is the
culprit - it's only designed to send a signal to the A/C amplifier, not
power a large relay directly.

Mine is set up so that the AC switch only drives a small ( 17 ma coil) relay
, and THAT relay drives the larger KUEP relay ( 100 ma coil). You could try
something like that.



A third possibility ( this seems unlikely to me) is that the blower switch
is faulty and is not grounding the heater relay ( which needs to be on to
power the AC switch) when teh blower switch is in the "high" position. Or,
if the ground wire from the heater switch were loose, it might have that
same effect (because there is more current through that ground wire when the
fan is on "high").


Phil




>From: Mark Dutko <[email protected]>
>Reply-To: [email protected]
>To: [email protected]
>Subject: Heater Relay Dropout Issue
>Date: Fri, 27 Jul 2007 06:49:38 -0700
>
>I have my heater relay for my 220V pack grounded on one 12v side and the
>other going to the positive wire of my heater fan through a switch in the
>dash which used to be the AC switch, When the AC switch is on and the fan
>is turned on the relay makes contact on the first, second and third fan
>speed position but on the fourth position or the highest, the relay drops
>out and I need to turn the fan off to get it to contact again. I have a
>diode across the relay coil (not sure if needed) and that's it. Any
>suggestions as to a fix for this and why it happens on the high fan speed
>setting?
>
>Thanks,
>
>Mark
>

_________________________________________________________________
http://newlivehotmail.com
 

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Discussion Starter #3
On some models the high side of the switch is feed through a different source of power and not through the resistor block that feeds the lower fan speeds. It might be dropping out because of that?

Tom


---- Mark Dutko <[email protected]> wrote:
> I have my heater relay for my 220V pack grounded on one 12v side and
> the other going to the positive wire of my heater fan through a
> switch in the dash which used to be the AC switch, When the AC switch
> is on and the fan is turned on the relay makes contact on the first,
> second and third fan speed position but on the fourth position or the
> highest, the relay drops out and I need to turn the fan off to get it
> to contact again. I have a diode across the relay coil (not sure if
> needed) and that's it. Any suggestions as to a fix for this and why
> it happens on the high fan speed setting?
>
> Thanks,
>
> Mark
>
 

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Discussion Starter #4
I think the most likely would be the switch but if it could handle
the draw from the relay it should continue to work as the relay draw
should remain the same? The wire to the relay is spliced right at the
motor and the AC switch has been completely isolated from the rest of
the car electronics. My 12v system runs off two 55A DC/DC and a med
sized aux battery. I will run some voltage tests later and see what
happens. Perhaps when I tested it the pack was disconnected and it
was on the aux battery only- I'll test again.



Thanks,

Mark



Phil Marino wrote:

> HI, Mark
>
> I've set up my Echo the same way ( using the AC switch to control
> the heater) so I'm familiar with the wiring.
>
> The fan takes a lot of current on high (about 12 amps) , so I can
> think of two possibilities:
>
>
> 1. Your 12V system voltage is dropping enough to drop the relay
> out. Put a voltmeter on your 12V system and watch the voltage as
> you change the fan speed.
>
> 2. There is enough voltage drop in the AC switch or wiring to
> allow the relay voltage to drop when the fan is on high.
>
> To check this, put a voltmeter on the relay coil and watch as you
> change fan speeds.
>
> What relay are you using?? It could be that the AC switch itself
> is the culprit - it's only designed to send a signal to the A/C
> amplifier, not power a large relay directly.
>
> Mine is set up so that the AC switch only drives a small ( 17 ma
> coil) relay , and THAT relay drives the larger KUEP relay ( 100 ma
> coil). You could try something like that.
>
>
>
> A third possibility ( this seems unlikely to me) is that the blower
> switch is faulty and is not grounding the heater relay ( which
> needs to be on to power the AC switch) when teh blower switch is in
> the "high" position. Or, if the ground wire from the heater switch
> were loose, it might have that same effect (because there is more
> current through that ground wire when the fan is on "high").
>
>
> Phil
>
>
>
>
>> From: Mark Dutko <[email protected]>
>> Reply-To: [email protected]
>> To: [email protected]
>> Subject: Heater Relay Dropout Issue
>> Date: Fri, 27 Jul 2007 06:49:38 -0700
>>
>> I have my heater relay for my 220V pack grounded on one 12v side
>> and the other going to the positive wire of my heater fan through
>> a switch in the dash which used to be the AC switch, When the AC
>> switch is on and the fan is turned on the relay makes contact on
>> the first, second and third fan speed position but on the fourth
>> position or the highest, the relay drops out and I need to turn
>> the fan off to get it to contact again. I have a diode across the
>> relay coil (not sure if needed) and that's it. Any suggestions as
>> to a fix for this and why it happens on the high fan speed setting?
>>
>> Thanks,
>>
>> Mark
>>
>
> _________________________________________________________________
> http://newlivehotmail.com
>
>
 

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Discussion Starter #5
Tom <[email protected]> wrote:

> On some models the high side of the switch is feed through a different
> source of power and not through the resistor block that feeds the lower
> fan speeds. It might be dropping out because of that?

My VW is also wired like this. When the fan is on HI, the switch actually
activates a relay that connects the blower motor directly to the 12V
system.

I used 4 diodes (1N4001?) to tap power directly from my fan speed switch,
but I did have to make a small wiring change for the HI setting. After the
diodes I have 3 switches that are activated by the temperature slider. As
you slide from "neutral" to "hot", the switches activate 1/2, 1, or 2 PTC
heater elements.

I know temperature output depends on airflow, but I don't like high flow
rates most of the time. And I don't like getting cooked when I need just a
little heat to keep the windshield defrosted :)

-Adrian
 
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