Originally Posted by grandmastem
I tapped into the grey/white wires for the A/C control. I was wondering if this is because I tapped into the grey/white wire? How would the fan function if I tapped into the purple, or would it?
The gray/white will make the fan cycle on every time the compressor clutch field coil has voltage applied.
The purple will make it run continuously whenever the A/C selector switch says that compressor operation is allowed
One gives you excessive on/off cycling of the fan motor and the other causes unnecessary continuous fan operation. Neither is an ideal solution but there are no other choices without adding more controls to the existing system.
The selector switch tells the PCM (by way of the purple wire) that it's permissible to run the A/C in several modes.
AC compressor operation allowed:
AC compressor operation not allowed: