Question
QUESTION: Hello, Matt.

Last year I had 4 new rainbird valves installed. They are Rainbird 100DV-F valves. I went to turn on my sprinklers for the 1st time yesterday and noticed one of the valves is not turning on, it just makes a slight buzzing sound at the valve.  I removed the wire from the sprinkler control and wired that valve into a different zone on the sprinkler control and it still doesn't come on. Also I tried turning the valve on manually and it still didn't work. Is the solenoid bad? Please let me know. Thanks. Steve

ANSWER: Thanks for the great info.
The "F" indicates flow-control. It is used the regulate the flow/ pressure of the sprinklers. In the center of the valve is a small knob. Turn it counterclockwise a few turns while the valve is active. It has a screwdriver slot on the top if you can't turn it by hand.
The buzzing noise you hear indicate the solenoid is getting power. So, wiring is not the problem. It is possible the drain port under the solenoid is plugged. If you want to check, turn the solenoid counterclockwise until you see water seeping out, then about 1/2 turn more. You can remove the solenoid completely, however you will get a spray of water out of the center. It may require turning off the water supply to put it back in.
If you have more question, please don't hesitate to ask.

---------- FOLLOW-UP ----------

QUESTION: Hi, Matt. Got the valve partly working. Now only 1 sprinkler out of the 3 on that zone that, that valve operates even works? I have never seen this before. Can the solenoid be causing this? Please let me know. Thanks.

ANSWER: It sound like the valve is either partially plugged or it is "regulating" pressure. Try turning the flow control all the way open then remove the solenoid. This should fully open the valve. If this cures the problem, then replace the top portion of the valve, it is defective. Is the valve very noisy compared to the others as if a lot of water was rushing by? This would indicate an obstruction in the inlet of the valve or the flow control is not opening fully. You need to remove the screws on the top of the valve and look for an obstruction and examine the diaphragm. When you turn the flow control screw you should see the diaphragm move up and down.  
The DV-100 is one of the most reliable valves, so my opinion leans toward an obstruction. I've saw small stones end up in a valve 4 years after it was installed.

---------- FOLLOW-UP ----------

QUESTION: OK, here is what I done. I removed the solenoid from one working valve and put it on the other valve, still the same. I removed the top of the valve and turned the water on and let the water spray up into the air about 30ft for about 1 minute, put the top back on, still same thing, I then swapped tops of valves, still same thing, only the one sprinkler working with the different valve top on. The flow control is completely open as it has been since they were installed. When the valves were running I opened the bleed screw to see if this would do anything, it doesn't. Never had this problem before. All the other zones and sprinklers are working properly. Also when the valve was apart I removed the diaphragm and flushed the valve that way. Didn't see any dirt or anything. Thanks.

Answer
Wow. You have tried everything with the valve. It's obvious the water is getting to the valve when you flushed it. The only thing I can think of with the valve is has a severe flaw in the lower half of the case and is just not capable of opening completely.
Have you removed the tops of the sprinklers with the water on just to check the flow to them? Or try placing your thumb over the nozzle of the operating head, the next head inline should pop-up. If it doesn't the you need to start checking the fittings at the sprinklers. I should have asked first,Is the system new or did you just have the valves changed? Did this zone ever work?
If you can give me a little more history, I'm sure we can resolve the problem.