About 2 months ago I received an inquiry about a Sanden SD7V16 control valve from a customer in Malaysia. After exchanging a few emails the order was placed and the product was shipped.

 
 

The Sanden SD7v16 is a variable displacement compressor used by several different manufacturers, most notably certain Volkswagon and Audi models. Here is a very nice article explaining how variable displacement compressors work.

 
 

But, I digress …

 
 

About 2 weeks after I shipped the control valve, our part number EX 10067, I received an email from our customer with “Wrong Item!!” in the subject line. The customer then proceeded to explain how we had erroneously shipped him an Ex 1210 which fits an SD7V12 rather than the EX 10067 he needed.

 
 

Taking the attitude that since he had it to look at and I didn’t and that it was quite possible the product was mis boxed, I simply shipped him a relacement part after I had verified with the manufacturer that I was indeed shipping the correct part and not one that was incorrectly packaged or labeled. Problem solved!

 
 

Or so I thought.

 
 

Two weeks or so go by and I receive an email with “Wrong Item AGAIN!!!” in the subject line. I think to myself “how could that be?” I verified I shipped the correct part with the manufacturer, so I send a return email questioning the customers reasons and logic.

 
 

He replied that if I look at the images I will note that the image depicting EX 10067 has a different “pin” coming out of its end than the image of EX 1210. The part I shipped him resembles the image of EX 1210, not that of the part he wanted, EX 10067.

 
 

 
 

Note that the valve on the left has a “pin” whose tip is smaller than the overall diameter of the rest of the pin and the valve on the right has a pin with a blunt end.

 
 

The customer was correct. What could be going on?

 
 

Puzzled, I decided to disassemble an intact compressor to see what was in it and confirm my suspicion that possibly the images were incorrect. No such luck! The images conformed to what my customer was telling me.

 
 

Now, both confused and irritated because I had specifically asked a supplier who also happens to be the manufacturer to confirm he sold me the correct valve, and he stated such was the case. I then purchased valves from 3 other suppliers to get to the bottom of this. All of them were the same.

 
 

Well, after an ungodly number of emails and phone calls I learned that the type of end on the valves “pin” doesn’t matter and for reasons unknown to me or anyone else, the engineers decided it was OK to use the same pin in all valves of this type. My guess is that the pin differences were for ease of identification on the parts shelf because that pin end is non functional, that is, it does not interact with any other component in the compressor. It merely sits in the open space between the valve plate and the rear head, as can be seen in this exploded view diagram of an SD7V16 compressor.

 
 

To his credit, my customer accepted my explanation and is going to use the valve. He also promised to report back on the results when the job is complete. I in turn wll note the outcome here, all of which only goes to prove that sometimes, even though it looks like a duck and quacks like a duck it might still be a chicken.

 
 

Thanks for listening.

 
 

Joe