SATC (A/C) diagnosis.

BudW

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I attached all of the SATC (Semi-Automatic Temperature Control) diagnosis pages, including flow charts, for those who would like it – from my ’86 FSM (Factory Service Manual) which is basically is the same for all years M and J-bodies.

If your servo motor is still working and on-car – but you have another electrical problem keeping it from working – Pages 24-51 “A” (fig. 8), “B” (Fig. 9-11) and “C” (on page 24-57)(Fig. 10) gives you instruction on how to move servo to full heat (called Full Reheat), full cold (called Minimum Reheat) or mid position (called Between Full and Minimum) – but not sure why you would want the mid position.

Page 24-63 gives a more details example of testing the servo motor, with it off of the car. When testing, make sure servo does turn to both max positions (fig. 10).
I took a spare servo plug-in, hooked up two battery leads to a 3 way rotary switch, for a mass testing tool – but if you are only testing 1 (or 2), using banana clipped jumper wires would be quicker.

Basically, the SATC wiring layout is simple (IMO):
- The middle wire (black wire from connector) is ground
- The white wire (from connector) is 12 volts
- The green wire with red tracer sends voltage with goes to the control head temperature section switch resistor, then to in car temperature sensor, then to ambient temperature sensor – back to the servo. That input uses the voltage from (or voltage drop from) the combination of the three before mentioned parts to move the servo motor to desired position. Matter of fact the servo motor is see-sawing or moving constantly back and forth – like looking at the top side of poorly made picket fence.

I do not see much problems with SATC systems, except for the servo or if someone (somehow) disconnected a electrical plug-in somewhere and left it that way.

Also vacuum hoses/vacuum connectors can cause problems (but that can be for either regular A/C or SATC cars).
BudW
 

Attachments

  • 86 FSM pg 24-51.pdf
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  • 86 FSM pg 24-52.pdf
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  • 86 FSM pg 24-53.pdf
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  • 86 FSM pg 24-54.pdf
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  • 86 FSM pg 24-55.pdf
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  • 86 FSM pg 24-56.pdf
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  • 86 FSM pg 24-57.pdf
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  • 86 FSM pg 24-58.pdf
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  • 86 FSM pg 24-59.pdf
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  • 86 FSM pg 24-60.pdf
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BudW

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Additional pages
 

Attachments

  • 86 FSM pg 24-61.pdf
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  • 86 FSM pg 24-62.pdf
    463.7 KB · Views: 539
  • 86 FSM pg 24-63.pdf
    488.3 KB · Views: 710
  • 86 FSM pg 24-64.pdf
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