Also, I discovered that when I start the car, the RPM is a bit over 1000 and after I start driving for a few minutes(with the A/C on) the RPM would drop to 600, sometimes even below 600. If the A/C is not on, the car sometimes idles around 400. Is this a normal idle speed?

 

One more question, when my mechanic was checking the rear A/C he mentioned that there were some wire harnesses that were not plugged in. Does anyone know what these unplugged wires are?