Can't understand code from my ford taurus!

I have a 1993 ford taurus 3.8L V6 automatic GL. I retrieved this code from my car using a innova ford OBD 1 digital code reader: code 634, manual lever position sensor voltage higher or lower than expected or A/C on. Can you tell me what this code means and what is wrong with my car?

Appears that the temperature selector for your A/C has a sensor on it that has failed. Or it could be a wiring issue,
check it out. It tells the computer to turn on the A/C compressor if you select defrost or Air Conditioning.

The code refers to either a problem with the park/neutral safety switch circuit, or with an electronically controlled transmission, a problem with the PRNDL (prindle) switch. Voltage too low when in park. The prindle switch is the indicator that reflects what gear the vehicle is in.