On Saturday, I returned to my car and found that I could not adjust the fan speed for the air conditioner. The fan control knob had broken. The plastic had cracked. After an email to Tesla, the service manager told me I could drop by, as they were open on Saturday till 5pm. I dropped by and they quickly replaced my fan control knob with a newer one with harder plastic. They also replaced the other two identical knobs: the temperature control and the air distribution control knobs. The early version of these knobs was made out of a weak plastic.