There is a module under the dash that controlls it. You can try replacing the module if you really want the intermittent feature to work. But it may also be a switch/wiring problem.
Yay, mine screws up everyonce in a while with the int speed. Its just the modual getting old 1ntegra says. Search for it cus was a ton of replies to another post on this problem…i just recommend getting rain-x or some other water repellent.