I just noticed this lately. When i start my car to let it warm up the fan come on almost right away. I noticed what sounds like the AC clicking every 30 seconds or so. Would this be the freon getting low? I know the fans run while the AC is on, so does the car think it is? I thought maybe temp sensor but im lost now.

 

Is the defrosters turned on? AC will turn on automatically with the front defrosters to remove moisture from the air. Fans come on automatically with AC being on. If the compressor cycles on for only a second or two every 30 secs or so, then that is likely a low freon charge. Could also be a faulty pressure sensor.

 

I had the switch all the way to the right for the front window defrost but not the rear window switch. It could be that simple. I will try it with just the heater only or off completely.

 

The rear window defrost has nothing to do with it. Strictly whether the front is on or off.

 

As stated above the system uses the dryer of the A/C System for the defroster.

 

It doesn't use the "dryer"... it uses the A/C evaporator coil to chill the air and knock out any excess moiture, then reheats the air with the heater coil, to insure that there is dry, unsaturated air hitting the windows.

 

No fans with the heater off. I had all kinds of thought running through my head so it nice to solve it so easy and with nothing to do or buy.