1997 Ford Ranger 4.0L with a heater/AC control problem.

1) In any position of the switch (defrost, panel, feet,etc.) the A?C comes on unless I have it unplugged at the compressor.
2) I have heat at the heater core, but little coming out the vents,defrost, etc.

I checked the panel switch, feet,defrost, AC switch (4 wires) and found that as I look at the plug there is a 1)red/orange, 2) black?, 3)small purple and a small 4)white purple tracer. Checking with an Ohm meter no mater what position the switch is in the only continuity is between 1 and 2. Does this sound correct?

 

Your observation for #1 & #2 is correct. That is the ground circuit for the blower motor and the blower relay coil.

You should have continuity between #3 & #4 in any position that is supposed to call for A/C compressor operation. That is ALL positions EXCEPT OFF, FLOOR and VENT.

What happens if you disconnect either fuse F18 (I/P), the low pressure cycling switch, the high pressure cutout switch, or the A/C WOT relay?

Steve

 

I didn't check #3 & #4 for continuity...dang. I will try that and the other ideas tomorrow and let you know. So #3 & #4 should be an open EXCEPT when in the A/C position, right?

 

Stated another way, 3 & 4 should be connected whenever compressor clutch operation is to be enabled. See above for the exclusions.

Steve

 

Checked pin #3 and #4 and they have continuity in heat mode so I guess I need a new switch....sigh.