I am baffled. I removed the climate control "slide" panel from the car and checked each slide position (low, medium and high) positions individually from the ground wire to the plug pins and all wires and plug pins have continuity. After checking the above, I hooked up the panel under the dash with the plug plugged in and the ground attached. When operated on the fan settings, the fan light comes on, but only one speed still comes on. After testing several times I got no speeds-the one speed just quit.
I removed the blower and tested each of the plug pins directly from the battery. That test revealed that all three speeds work perfectly from direct power. So, the panel slides make contact and have continuity to the plug and the blower speeds do work but not together. That leaves the wiring from the 6 prong plug under the dash and the 4 wire plug that operates the blower. The wiring diagram shows every wire and I have confirmed the wire colors and they are accurate. I will now try to figure out how to go around the original plug under the dash and the 4-hole plug to the blower. Not sure what else to try.
