[MBZ] Mono valve voltage readings -please help

[Mike Esh]

I am still having trouble regulating heat in my 84 300D.  I either get all heat 
or all cold.  Cold only coming on when temp wheel is rotated all the way to max 
cool.

Current readings are at Mono valve are as follows:
12 volts when system is off. 

System on any of the 3 center buttons pushed:
12 volts when temp wheel is set to full cool or full heat.   zero volts when 
temp dial  is moved to any other position.

Zero volts when defrost button is pushed.

Is this correct? Any suggestions?

I have replaced mono valve already.
Thanks, 
Mike
Michael E. Esh


___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Rich Thomas]

Sounds like the control unit is not controlling.  Might want to take it 
out and see if anything on it (like maybe the wheel contacts) is 
corroded, broken, fried, worn out, whatever.


--R

On 11/30/11 12:24 PM, Mike Esh wrote:

I am still having trouble regulating heat in my 84 300D.  I either get all heat 
or all cold.  Cold only coming on when temp wheel is rotated all the way to max 
cool.

Current readings are at Mono valve are as follows:
12 volts when system is off.

System on any of the 3 center buttons pushed:
12 volts when temp wheel is set to full cool or full heat.   zero volts when 
temp dial  is moved to any other position.

Zero volts when defrost button is pushed.

Is this correct? Any suggestions?

I have replaced mono valve already.
Thanks,
Mike
Michael E. Esh


___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com



___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[andrew strasfogel]

If you remove the temperature wheel (quite easy) you can inspect for breaks
in the circuitry.  Then swap it with a temperature reel from another ACC
module.  That worked for me.

On Wed, Nov 30, 2011 at 12:36 PM, Rich Thomas <
richthomas79td...@constructivity.net> wrote:

> Sounds like the control unit is not controlling.  Might want to take it
> out and see if anything on it (like maybe the wheel contacts) is corroded,
> broken, fried, worn out, whatever.
>
> --R
>
>
> On 11/30/11 12:24 PM, Mike Esh wrote:
>
>> I am still having trouble regulating heat in my 84 300D.  I either get
>> all heat or all cold.  Cold only coming on when temp wheel is rotated all
>> the way to max cool.
>>
>> Current readings are at Mono valve are as follows:
>> 12 volts when system is off.
>>
>> System on any of the 3 center buttons pushed:
>> 12 volts when temp wheel is set to full cool or full heat.   zero volts
>> when temp dial  is moved to any other position.
>>
>> Zero volts when defrost button is pushed.
>>
>> Is this correct? Any suggestions?
>>
>> I have replaced mono valve already.
>> Thanks,
>> Mike
>> Michael E. Esh
>>
>>
>> __**_
>> http://www.okiebenz.com
>> For new and used parts go to www.okiebenz.com
>> To search list archives 
>> http://www.okiebenz.com/**archive/
>>
>> To Unsubscribe or change delivery options go to:
>> http://mail.okiebenz.com/**mailman/listinfo/mercedes_**okiebenz.com
>>
>>
> __**_
> http://www.okiebenz.com
> For new and used parts go to www.okiebenz.com
> To search list archives 
> http://www.okiebenz.com/**archive/
>
> To Unsubscribe or change delivery options go to:
> http://mail.okiebenz.com/**mailman/listinfo/mercedes_**okiebenz.com
>
___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Fmiser]

> Mike Esh wrote:

> Current readings are at Mono valve are as follows:
> 12 volts when system is off. 

The monovalve is not controlled with a steady voltage.  12V is
switched on and off rapidly, called pulse width modulation.
That is, the more heat requested, the longer the OFF pulse and
the shorter the ON pulse.

> System on any of the 3 center buttons pushed:
> 12 volts when temp wheel is set to full cool or full heat.
> zero volts when temp dial  is moved to any other position.

A DC volt meter is not a very dependable way to measure the
control signal. The measured voltage will depend on the specs.
of the meter. An oscilloscope is best.  I suppose a ignition
dwell meter would work.  Do you have one of those?

> Zero volts when defrost button is pushed.

Defrost is the fail mode.  So when there is no power to the
monovalve, and no vacuum to the servos the system will be in
full heat, defrost mode.  So this point is correct.

> Is this correct? Any suggestions?

Without an oscilloscope - or maybe a dwell meter - swapping out
parts may be the best option.  I saw an hardware kit that will
turn an iPad into a oscilloscope...

--   Philip

___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Jim Cathey]

...Zero volts when defrost button is pushed.


No voltage == heat, +12V == no heat.  PWM (in the seconds timeframe)
for in between.  If it's never getting juice, the valve is not your
problem and you need to look at, say, resoldering the control panel.
(Oh, and fuses, temperature feedback plumbing, etc.)

-- Jim



___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Mitch Haley]

Jim Cathey wrote:

No voltage == heat, +12V == no heat.  PWM (in the seconds timeframe)
for in between.  


Do you mean that duty cycle is measured with s stopwatch, not with a dwell 
meter?

Mitch.

___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Dan Penoff]

I believe a dwell meter would give you an average of the duty cycle, so you 
would see as it increased or decreased.

Essentially, the signal is a square wave with the time being varied to control 
the flow of coolant through the valve.

Dan

Sent from my iPhone

On Dec 1, 2011, at 6:50 AM, Mitch Haley  wrote:

> Jim Cathey wrote:
>> No voltage == heat, +12V == no heat.  PWM (in the seconds timeframe)
>> for in between.  
> 
> Do you mean that duty cycle is measured with s stopwatch, not with a dwell 
> meter?
> 
> Mitch.
> 
> ___
> http://www.okiebenz.com
> For new and used parts go to www.okiebenz.com
> To search list archives http://www.okiebenz.com/archive/
> 
> To Unsubscribe or change delivery options go to:
> http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Jim Cathey]

Do you mean that duty cycle is measured with s stopwatch, not with a 
dwell meter?


Neither, I think.  It's right at that in-between stage
where a regular meter can't really keep up, yet is too
slow for the typical (?) dwell meter.  I found that a 12V
test lamp worked perfectly.  Just watch it blink on and off.
The fast-reacting analog gauge on a Fluke DMM tracked it
OK, but wasn't nearly as easy to keep track of as the lamp.

-- Jim



___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Alex Chamberlain]

On Dec 1, 2011 6:51 AM, "Jim Cathey"  wrote:
>>

> slow for the typical (?) dwell meter.  I found that a 12V
> test lamp worked perfectly.  Just watch it blink on and off.

But a 'scope is so much more fun!

Alex
___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Mike Esh]

Jim,
I hooked a taillight bulb to the leads going to the mono valve and still get 
the same readings I did with the multimeter.  I did not get blinking lights at 
any settings, solid on, solid off.  I hooked up five different control boxes 
and got the same results.  
I am at a loss.
Mike

Michael E. Esh


On Dec 1, 2011, at 12:23 AM, Jim Cathey  wrote:

>> ...Zero volts when defrost button is pushed.
> 
> No voltage == heat, +12V == no heat.  PWM (in the seconds timeframe)
> for in between.  If it's never getting juice, the valve is not your
> problem and you need to look at, say, resoldering the control panel.
> (Oh, and fuses, temperature feedback plumbing, etc.)
> 
> -- Jim
> 
> 
> 
> ___
> http://www.okiebenz.com
> For new and used parts go to www.okiebenz.com
> To search list archives http://www.okiebenz.com/archive/
> 
> To Unsubscribe or change delivery options go to:
> http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Mike Esh]

I tried five different control units.  I cleaned each one with contact cleaner. 
 Could they all be bad?


Michael E. Esh


On Nov 30, 2011, at 12:36 PM, Rich Thomas 
 wrote:

> Sounds like the control unit is not controlling.  Might want to take it out 
> and see if anything on it (like maybe the wheel contacts) is corroded, 
> broken, fried, worn out, whatever.
> 
> --R
> 
> On 11/30/11 12:24 PM, Mike Esh wrote:
>> I am still having trouble regulating heat in my 84 300D.  I either get all 
>> heat or all cold.  Cold only coming on when temp wheel is rotated all the 
>> way to max cool.
>> 
>> Current readings are at Mono valve are as follows:
>> 12 volts when system is off.
>> 
>> System on any of the 3 center buttons pushed:
>> 12 volts when temp wheel is set to full cool or full heat.   zero volts when 
>> temp dial  is moved to any other position.
>> 
>> Zero volts when defrost button is pushed.
>> 
>> Is this correct? Any suggestions?
>> 
>> I have replaced mono valve already.
>> Thanks,
>> Mike
>> Michael E. Esh
>> 
>> 
>> ___
>> http://www.okiebenz.com
>> For new and used parts go to www.okiebenz.com
>> To search list archives http://www.okiebenz.com/archive/
>> 
>> To Unsubscribe or change delivery options go to:
>> http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
>> 
> 
> ___
> http://www.okiebenz.com
> For new and used parts go to www.okiebenz.com
> To search list archives http://www.okiebenz.com/archive/
> 
> To Unsubscribe or change delivery options go to:
> http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Curt Raymond]

Are any of the control boxes (you mean the push button array here right?) known 
to be good? Like you can put them in another car and they for sure work?
The problem is you're suffering just about the most common failure. If all the 
boxes you're messing with are 20+ years old its quite possible for them all to 
be broken the same...

-Curt

Date: Thu, 01 Dec 2011 17:50:14 -0500
From: Mike Esh 
To: Mercedes Discussion List 
Subject: Re: [MBZ] Mono valve voltage readings -please help
Message-ID: <93499b2d-4baa-47bf-8e14-97aece39f...@me.com>
Content-Type: text/plain; CHARSET=US-ASCII

Jim,
I hooked a taillight bulb to the leads going to the mono valve and still get 
the same readings I did with the multimeter.  I did not get blinking lights at 
any settings, solid on, solid off.  I hooked up five different control boxes 
and got the same results.  
I am at a loss.
Mike

Michael E. Esh


On Dec 1, 2011, at 12:23 AM, Jim Cathey  wrote:

>> ...Zero volts when defrost button is pushed.
> 
> No voltage == heat, +12V == no heat.  PWM (in the seconds timeframe)
> for in between.  If it's never getting juice, the valve is not your
> problem and you need to look at, say, resoldering the control panel.
> (Oh, and fuses, temperature feedback plumbing, etc.)
> 
> -- Jim
> 

___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Jim Cathey]

I tried five different control units.  I cleaned each one with contact 
cleaner.  Could they all be bad?


Absolutely.  The units with the little translucent AUTO switch
are EXTREMELY prone to having cracked solder joints.  As in: I've
had to fix EVERY one of them in our fleet.  Yes, every one.
Fortunately the repair is fairly easy, if you can solder.

-- Jim



___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Jim Cathey]

I hooked a taillight bulb to the leads going to the mono valve and 
still get the same readings I did with the multimeter.  I did not get 
blinking lights at


Taillight bulb is a bit heavy, a side-marker lamp would be
kinder and gentler.

any settings, solid on, solid off.  I hooked up five different control 
boxes and got the same results.


On our 380SL the auxiliary coolant pump is a bit noisy and you
can hear a faint 'whirr' inside the cabin.  As the monovalve cycles
on and off you can hear the pitch of the whirr change.
"Whee-whirr-whee-whi..."

-- Jim



___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Mike Esh]

Here is good conversation about mono valve voltage.  It cleared things up me 
about reading voltage to the mono valve.  Mine appears to be working correctly.

Michael E. Esh


On Dec 1, 2011, at 9:11 PM, Jim Cathey  wrote:

>> I hooked a taillight bulb to the leads going to the mono valve and still get 
>> the same readings I did with the multimeter.  I did not get blinking lights 
>> at
> 
> Taillight bulb is a bit heavy, a side-marker lamp would be
> kinder and gentler.
> 
>> any settings, solid on, solid off.  I hooked up five different control boxes 
>> and got the same results.
> 
> On our 380SL the auxiliary coolant pump is a bit noisy and you
> can hear a faint 'whirr' inside the cabin.  As the monovalve cycles
> on and off you can hear the pitch of the whirr change.
> "Whee-whirr-whee-whi..."
> 
> -- Jim
> 
> 
> 
> ___
> http://www.okiebenz.com
> For new and used parts go to www.okiebenz.com
> To search list archives http://www.okiebenz.com/archive/
> 
> To Unsubscribe or change delivery options go to:
> http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Mike Esh]

None of the pbu's are known to be good.  I am going to check mono valve 
function one more time and then order new pbu if I find nothing new.  Does 
Rusty carry these?

Michael E. Esh


On Dec 1, 2011, at 7:56 PM, Curt Raymond  wrote:

> Are any of the control boxes (you mean the push button array here right?) 
> known to be good? Like you can put them in another car and they for sure work?
> The problem is you're suffering just about the most common failure. If all 
> the boxes you're messing with are 20+ years old its quite possible for them 
> all to be broken the same...
> 
> -Curt
> 
> Date: Thu, 01 Dec 2011 17:50:14 -0500
> From: Mike Esh 
> To: Mercedes Discussion List 
> Subject: Re: [MBZ] Mono valve voltage readings -please help
> Message-ID: <93499b2d-4baa-47bf-8e14-97aece39f...@me.com>
> Content-Type: text/plain; CHARSET=US-ASCII
> 
> Jim,
> I hooked a taillight bulb to the leads going to the mono valve and still get 
> the same readings I did with the multimeter.  I did not get blinking lights 
> at any settings, solid on, solid off.  I hooked up five different control 
> boxes and got the same results.  
> I am at a loss.
> Mike
> 
> Michael E. Esh
> 
> 
> On Dec 1, 2011, at 12:23 AM, Jim Cathey  wrote:
> 
>>> ...Zero volts when defrost button is pushed.
>> 
>> No voltage == heat, +12V == no heat.  PWM (in the seconds timeframe)
>> for in between.  If it's never getting juice, the valve is not your
>> problem and you need to look at, say, resoldering the control panel.
>> (Oh, and fuses, temperature feedback plumbing, etc.)
>> 
>> -- Jim
>> 
> 
> ___
> http://www.okiebenz.com
> For new and used parts go to www.okiebenz.com
> To search list archives http://www.okiebenz.com/archive/
> 
> To Unsubscribe or change delivery options go to:
> http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Mike Esh]

Does anyone have a picture example of a broken circuit?  Am I just looking for 
crack in a solder joint?

Michael E. Esh


On Dec 1, 2011, at 9:09 PM, Jim Cathey  wrote:

>> I tried five different control units.  I cleaned each one with contact 
>> cleaner.  Could they all be bad?
> 
> Absolutely.  The units with the little translucent AUTO switch
> are EXTREMELY prone to having cracked solder joints.  As in: I've
> had to fix EVERY one of them in our fleet.  Yes, every one.
> Fortunately the repair is fairly easy, if you can solder.
> 
> -- Jim
> 
> 
> 
> ___
> http://www.okiebenz.com
> For new and used parts go to www.okiebenz.com
> To search list archives http://www.okiebenz.com/archive/
> 
> To Unsubscribe or change delivery options go to:
> http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Rick Knoble]

On Dec 1, 2011, at 8:53 PM, "Mike Esh"  wrote:

> Does anyone have a picture example of a broken circuit?  Am I just looking 
> for crack in a solder joint?

Here is a pictorial on disassembly from Dan. I don't think it shows 
specifically cracks, but it was pretty thorough, IIRC. (can't view it on the 
iPhone for some reason). 

http://gallery.me.com/dpenoff#100140

BTW, do you want to part with one of the non-functioning units? I could use a 
spare. 
Rick
Sent from my iPhone



___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Jim Cathey]

order new pbu if I find nothing new.  Does Rusty carry these?


You got a big wallet?  There's a reason that we all
either resolder them, or learn to do so.  Hey, you've
got five to learn on...

-- Jim



___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Jim Cathey]

Does anyone have a picture example of a broken circuit?  Am I just 
looking for crack in a solder joint?


Open one up, and examine (in particular) the joints to
the side boards, which are (in contravention to all known
good soldering practice) also the mechanical support of
the side boards.  The cracks there are usually extremely
obvious.

However, often those are not the only cracked joints.
Just the most obvious ones.

-- Jim



___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

Re: [MBZ] Mono valve voltage readings -please help

[Mike Esh]

Yes, send me our address.

Michael E. Esh


On Dec 1, 2011, at 10:05 PM, Rick Knoble  wrote:

> On Dec 1, 2011, at 8:53 PM, "Mike Esh"  wrote:
> 
>> Does anyone have a picture example of a broken circuit?  Am I just looking 
>> for crack in a solder joint?
> 
> Here is a pictorial on disassembly from Dan. I don't think it shows 
> specifically cracks, but it was pretty thorough, IIRC. (can't view it on the 
> iPhone for some reason). 
> 
> http://gallery.me.com/dpenoff#100140
> 
> BTW, do you want to part with one of the non-functioning units? I could use a 
> spare. 
> Rick
> Sent from my iPhone
> 
> 
> 
> ___
> http://www.okiebenz.com
> For new and used parts go to www.okiebenz.com
> To search list archives http://www.okiebenz.com/archive/
> 
> To Unsubscribe or change delivery options go to:
> http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com

___
http://www.okiebenz.com
For new and used parts go to www.okiebenz.com
To search list archives http://www.okiebenz.com/archive/

To Unsubscribe or change delivery options go to:
http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com