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The ACAC diagnostic mode is meant for diagnosing the ACAC. It has pcm info but only because this info is used to diagnose the AC system. Things like engine coolant temp, ambient air temp, engine load, etc.
You're probably better off using an aldl scan tool.
 

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91-93 AC code reading

From http://buickforums.com/forums/showthread.php?t=13953
here's the simple set of AC trouble codes accessible in 91-93 RMs (and presumably OCCs):

From the 91 FSM:

SELF-DIAGNOSTIC FEATURES
If the self-diagnostics feature of the automatic air conditioning system detects a fault while the system is operating, the "°F/°C" symbol to the right of the temperature number will flash very rapidly and the appropriate fault code will be produced by the control assembly microprocessor.
With the exception of Fault Code 09 (Low Freon), fault codes will not be stored in the microprocessor.
As soon as a fault has been detected, the control assembly microprocessor will use a default value (as a parameter value) until the fault is no longer detected.

ENTERING DIAGNOSTIC MODE
To enter the diagnostic mode, the "EXT TEMP" touch switch must be pressed and held while the "OFF" switch is then pressed to enter the command (normally within 5 seconds). Upon entry into the diagnostic mode, the LCD will display any fault codes that are present.

DTC DESCRIPTION
Codes 01/02 Temperature Air Valve Actuator Motor Circuit Fault
Code 03 Outside Air Temperature Sensor Circuit Open
Code 04 Outside Air Temperature Sensor Circuit Short
Code 05 Inside Air Temperature Sensor Circuit Open
Code 06 Inside Air Temperature Sensor Circuit Short
Codes 07/08 Sun Load Sensor Circuit Open or Short
Code 09 Low Freon
Code 10 UART Failure

Clearing Trouble Codes
With the exception of Fault Code 09 (Low Freon), fault codes will not be stored in the microprocessor.
When fault code "09" (Low Freon) is displayed, the fault code can be cleared after servicing the refrigerant system by pressing the "OFF" touch switch while in the diagnostic mode. This also will enable the compressor circuit.
 

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after reading this thread i tried to look at the codes, tach, speedo, etc in my climate control like everyone has stated, no matter what number i go to when i hit the middle button (enter) it just sits on zeros, wonder whats up with that? is it not talking to the computer or something of that sort?
 

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Ok i tried this for an abs light on my 92 RMS. In -04 menu it shows 118. I looked up 118 it shows cooloing system problem.
 

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