is this supposed to do that?.. if it does i must not have ever noticed it.. my heater valve is actuating every like 5 seconds or so when i turn the key to the on position without starting the car.. i can hear/feel it doing it from inside and i can feel it if i grab it. the heater dial was at about 10 o'clock position at the time..
It's supposed to cycle at about a 4-5 second interval. This will depend on the heater core temp compared to the cabin temp and the setting of the control dial. Probably if you turn the dial all the way cold you would stop hearing the "thump" of the valve actuating.
