I am taking a more serious look in to this...........

Denso claimed these are the current marking if diode is built-in into the control valve solenoid.

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Zoomed.



I have found only the triangle marking so far, could not find the so called 5 dots.



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Pine Holllow image below , from ML/GL black mercedes.



I managed to get my hand on a used Denso compressor.
Initially I thought the smiley is the 5 dots, IT IS NOT !!!!
The 5 dots is supposed to be under the "curve" of the plastic body.




The one on my E400, also has a smiley...duggh !!!!



So I tested the Control Valve I got, it came from this compressor :



I traced its Denso P/N and found supposedly which car the above compressor comes from.
I managed to download Denso Internal training material , them f-kers use the trick below :

I have included 3 documents from Denso, 1 is open to public Control Valve indentification PDF.
2 is their internal training docs, which I have to zip because it can't be uploaded here for some reason.<<<<---- enjoy thesr 2 docs my man


Carry on...............

So i found the MB car this compressor is used for


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Using EPC, let's track this compressor user models


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The Control Solenoid


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Will continue......................

 

So I tried testing the Control Valve with regular DMM, I know it won't work, but I must try.
It does not work, be it in Ohms mode or Diode mode. I mean we can't tell of there is a diode....even though I place a diode in flyback configuration, see below Wiki image.

The DMM will see the solenoid as resistance, even though it is an inductor.
So diode being there has no effect on reading, even if you flip the leads during diode test or Ohms test.



L & R is the control valve or solenoid.


No choice, the only way to test is to see the massive voltage kick back when a solenoid is being TURNED off and has no diode.
Solenoid when turned off it is an electromagnetic "battery", and produces high voltage, that is how ignition COP works, when it is being TURNED OFF and not when it is being turned ON or energized.
So the diode absorb the high voltage from a TURNED OFF solenoid or any coil like relay coil etc etc ...as long as there is a coil.

So got to use oscillosope.


The aircon control solenoid without a flyback diode is SO VIOLENT !!!!

This test, no diode installed. I set my power supply to 12V and 1 amp only.
I am sending 3 second power only at the most and DC , not PWM pulses.




NO DIODE ---TURNING CONTROL VALVE OFF
The spike is very short, less than 2 millisecond of 2/1,000 second, but see -200V and +193V



NO DIODE -----Powering ON if connector is loose. Those high voltage spike I call bounce, because loose connector is like fast On-Off-On-Off




Powering ON with fast direct no loose fit on connector.




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With 2 amps diode. Diode is inside the clear hose.


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WITH DIODE - Turning on control valve solenoid




WITH DIODE - Turning off control valve solenoid




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Our HVAC computer, N22/7 when it does not have built in diode for suppression of this spike and your mistakenly bought a Control Valve without diode, N22/7 will produce DTC and not allow compressor to be powered.
Bye bye cold and welcome sweaty azz.

Good Case study here : Pine Hollow on an MB GL/ML

First video is a misdiagnose and junkyad N22/7 computer was purchased

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Part 2 is the solving of the case.




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Old Denso control valve with diode has YELLOW DOT. Found in MB cars of 2004.



Enjoy his video. Very informative




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