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For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 1997 🢒 Sun Runner - 4WD (Canada) 🢒 Engine 🢒 Engine Controls - 1.6L 🢒 Air Conditioning (A/C) Idle Circuit Diagnosis

Object Number: 1558208 Size: SF
Engine Controls Schematics

Circuit Description

This signal is sent from the A/C compressor control module. The powertrain control module (PCM) detects whether or not the A/C system is operating via the A/C compressor control module. The extra load the A/C system demands from the engine requires a higher idle speed. When the PCM receives the A/C ON signal, it will activate the Idle Air Control (IAC) valve and the idle speed will increase.

Diagnostic Aids

An intermittent malfunction may be caused by a fault in the A/C sensor circuit. Inspect the wiring harness and components for any of the following conditions:

    • Backed out terminals.
    • Improper mating of terminals.
    • Broken electrical connector locks.
    • Improperly formed or damaged terminals.
    • Faulty terminal to wire connections.
    • Physical damage to the wiring harness.
    • A broken wire inside the insulation.
    • Corrosion of electrical connections, splices, or terminals.

Use a scan tool in order to monitor the A/C switch parameter. When the A/C switch is in the ON position and the blower speed is in any speed except OFF, the scan tool should read ON. When the A/C switch is OFF, the scan tool should read OFF.

Test Description

The numbers below refer to the step numbers in the Diagnostic Table.

  1. This step checks for an open or a short to ground in the YEL/BLK wire, or a faulty PCM.

    2.

  2. This step checks for a faulty PCM or for a faulty A/C compressor control module.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Turn OFF the ignition.
  2. Disconnect the A/C compressor control module electrical connector.
  3. Turn ON the ignition.
  4. Using a DMM, measure the voltage from the A/C compressor control module connector cavity 1.

Does the DMM read within the specified value?

B+

Go to Step 3

Go to Step 4

3

  1. Turn OFF the ignition.
  2. Reconnect the A/C compressor control module electrical connector.
  3. Start the engine.
  4. Press the A/C switch to ON and move the blower speed selector switch to any position except OFF.
  5. Using a DMM, back probe the A/C compressor control module connector cavity 1.
  6. Measure the voltage.

Does the DMM read within the specified value?

0 volts

System OK

Go to Step 5

4
  1. Check for an open or a short in the A/C ON signal circuit between the A/C compressor control module and the PCM.
  2. Repair as necessary.

Was a repair necessary?

--

Go to Step 7

Go to Step 6

5

Replace the A/C compressor control module. Refer to Air Conditioning.

Is the action complete?

--

Go to Step 7

--

6

Replace the PCM. Refer to Powertrain Control Module Replacement

Is the action complete?

--

Go to Step 7

--

7

Operate the vehicle within the conditions under which the original symptom was noted.

Does the system now operate properly?

--

System OK

Go To Diagnostic Aids