Its simple. Just lift up the hood, look back on the back of your firewall on the pass side. Its a rubber tube that runs down, take your fingers and press down from where it starts to where it ends, if u feel that its clogged then just take a hose and shoot it through to unclog it, Most likely, its at the bottom where the end of the hose gets smaller to keep things from getting up in there and to get a constant stream of water, but it makes it very easy to clog up, I just cut off the last inch. Works fine now. I had a whole bunch of crud up in there.
Currently: '14 JKU
Past vehicles: '92 YJ, '97 TJ, '10 JK