So my rear defrost switch is starting to act up or something is causing it to not work properly. When the car is started and I turn on the rear defrost I can hear the relay click up under the dash. Sometimes the click to turn on is a slower. While the rear defrost is activated I can hear it clicking every few minuets. This all with the lights off and the blower motor on. Once I turn the lights on but the blower motor off it is a different story. The light stays on but then after a few minuets you can here a click and the light flashes. Turn lights off and it stops flashing sometimes. Sometimes after the light is flashing it doesn't matter what you do, turn everything off for instance, when you press the switch it just flashes until you leave it off for a while. It seems to be like a load issue maybe. Is there a relay for the HVAC itself? What is the model number for the rear defrost relay? Of course this happens in the winter when you actually are going to really use it.