that's an easy one.
what you should've done is clicked that little SEARCH button....but anyhow...
-check the heater fuse
-if the fuse is okay, check the solenoid valves. pop the hood, give contact 2, and have someone turn the hot-cold dial. you must listen if it's clicking. it's the little plastic cover next to the fuse box under the hood. it's located just in front of the driver's side.
if they don't click, then they're ready for replacing.