Originally Posted by tangofox007

Reference the subject vehicle, yes. Perhaps your comments were in reference to some other unspecified model. The thread that you referenced was discussing an '86 300 SDL. I am not sure how that relates to questions posed by the originator of this thread.

On the '82 300 SD, there are two switches on the receiver/dryer-the r/d temperature switch and the compressor low pressure cut-out switch. The temp switch closes at 126 degrees F, energizing the aux fan via the aux fan relay. The low pressure cut-out switch opens if the refrigerant pressure drops below 10 psi, removing power from the a/c compressor. The pressure switch is not directly tied to the operation of the aux fan. The fan is either off or on; it does not run at multiple speeds.