Clicking/knocking noise on 1996 Cherokee

I have a 1996 Jeep Cherokee that I have unfortunately fallen for in a serious way. At this point I have spent more on repairing the vehicle than I paid for the vehicle. Regardless, I look at preventative work on the jeep. As of right now it runs fine, except for a few noises.

I have a clicking or knocking noise that increases and decreases with the speed of the engine. I have located the clicking engine piece, but could not find it in my Chilton’s manual. The item is plugged into the electrical system and has rubber hoses going to the charcoal filter and then to an air manifold…not sure if it is intake or outgoing, but it is attached to the block near the air temperature sensor. The knocking is loud enough for me to hear it in the drivers seat.

I can take a picture and post the item, but I do not know where to post the picture. Regardless, what is this device and what can this clicking indicate?

I checked a jeep forum out of curiosity…and there is a post commenting a similar issue with a picture of the offending device. The forum states it is the Purge Control Solenoid and the noise is normal.

Just as a note for future people…the picture of in the link shows the PCS near the master cylinder, but it is in different places in different jeeps. Mine is near the expansion valve for the AC system.