I have a Hunter mini-click rain sensor wired (not wireless) that was with my previous system. I found the instructions where there are supposed to be 2 yellow wires, 1 white, and 1 blue wire. I have 2 yellow wires but apparently the sprinkler installer used a different wire because I have 1 red and 1 black wire. How do I determine how those match up to the white and blue wires?
@dcwebman - wired sensors normally only have two wires and just open up the circuit. Are you sure the rain sensor is wired all the way from the sensor to the unit?
My guess is put the red and black wires where the white and blue wires go. I don’t think it matters, but if it doesn’t work in the first configuration one can switch the location of the red and black wires. The yellow wires should be the power for the device.
When generation of Rachio are you installing it on?
Can any pictures of the Hunter be posted for confirmation?
Thank you for the reply. I am pretty sure the sensor is wired all the way because it did stop the timer from running when it rained.
It is a Rachio 3 and I am attaching a photo of the Hunter.
The wiring for the Rachio 3 is supposed to be white & one yellow on VAC-, other yellow on VAC+, and Blue on S1. I thought like you that it shouldn’t matter mixing up the white and blue. If it didn’t work, I would just switch them. Apparently that was the wrong idea.
I could not get the Rachio to connect to wifi. So I touched the rain sensor wires to make sure they were connected tightly, saw some sparks from the connections, and nothing from that point so the circuit board must have been fried. I wanted to get the job done so I purchased another Rachio 3, DIDN’T connect the rain sensor that time, and it worked fine right away. So I am hesitant to guess again on the rain sensor wires. 
When I started up the new one to connect to wifi, the lights were flashing across the middle and I know I did not see that the first time. I don’t know if hooking up the rain sensor blocked the ability to connect to wifi or even operate correctly. Perhaps there was something wrong with the first Rachio 3, but I don’t want to damage the second one to see.
@dcwebman - don’t use the yellow wires!! The yellow wires go to an external power supply to power the old controller. The Rachio uses it’s own power adapter.
Just put the white and blue wires in 24V- and S1 - doesn’t matter which one is which.
Also, contact Rachio support about a RMA for the original device. They’ve been pretty good on that.
Wow, that is extremely confusing! The instructions refer to 2 yellow wires which obviously these were and not plugged in elsewhere. They even are both labeled 24VAC. Thanks so much for the help. I will contact Rachio support.