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A/c Compressor Clutch Controls Chevrolet Lumina I

A/c Compressor 11 illustrations ~1415 words

MODEL IDENTIFICATION

Body Designation (1)Model
"W" BodyCutlass Supreme, Grand Prix, Lumina, Monte Carlo & Regal
(1) Body codes determined by fourth character of VIN code.
(1)Body codes determined by fourth character of VIN code.

BODY CODE DESIGNATIONS

DESCRIPTION & OPERATION

To improve idle quality and Wide Open Throttle (WOT) performance, and for system protection, the A/C compressor clutch is controlled by the Powertrain Control Module (PCM).

A refrigerant pressure sensor is used to indicate high and low side refrigerant pressure to the PCM for controlling cooling fan, A/C compressor clutch and Idle Air Control (IAC) valve. If a fault is detected in refrigerant pressure circuit, A/C compressor clutch will be disabled.

The A/C compressor clutch relay is controlled by the PCM. This allows the PCM to raise idle speed before engaging compressor clutch, and disable compressor clutch during WOT, high engine RPM, high power steering loads and hot engine restarts. PCM also disables compressor clutch if coolant temperature becomes excessive.

TROUBLE SHOOTING

Note. This article contains test charts which are part of General Motors Computerized Engine Controls. Only those charts required to test A/C compressor clutch control are included. Other diagnostic information may be referenced while performing A/C compressor clutch control diagnosis. For complete information on General Motors Computerized Engine Control systems, see the appropriate G-TESTS W/CODES article in the ENGINE PERFORMANCE section.

TESTS W/CODES - 3.4L - Except Regal

TESTS W/CODES - 3.8L - Regal

Trouble shoot A/C compressor clutch control using appropriate schematic and diagnostic charts. See TROUBLE SHOOTING CHART DIRECTORY. See A/C COMPRESSOR CLUTCH RELAY LOCATION table for A/C compressor clutch relay location.

RELAY LOCATION

ApplicationLocation
"W" BodyIn Underhood Fuse/Relay Block, Forward Of Right Front Strut Tower

A/C COMPRESSOR CLUTCH RELAY LOCATION

TROUBLE SHOOTING CHART DIRECTORY

ApplicationSee Figure
3.1L VIN M(Scheme 1) - (Scheme 3)
3.4L VIN X(Scheme 4) - (Scheme 7)
3.8L VIN L(Scheme 8) - (Scheme 11)

A/C COMPRESSOR CLUTCH CHART INDEX

SCAN TESTER

A variety of information is transmitted through Data Link Connector (DLC) terminal "E" or "M", depending on engine. This data is transmitted at a high frequency which requires a Tech 1 scan tester for interpretation. Several scan testers are available for diagnostic work. Scan testers other than Tech 1 scan tester will function and provide information for diagnostic work; however, some charts will specify a Tech 1 scan tester. Failure to use a Tech 1 scan tester when specified may result in incorrect diagnosis of a system.

CHART C-10 - A/C COMPRESSOR CLUTCH CIRCUIT DIAGNOSIS

3.1L - VIN M

A/C compressor clutch relay is controlled by the Powertrain Control Module (PCM). The PCM provides a ground on circuit No. 459 and A/C is requested. PCM will delay A/C compressor clutch engagement momentarily after A/C is requested. This delay allows Idle Air Control (IAC) valve to adjust engine RPM for additional load.

PCM will temporarily disengage A/C compressor clutch for a precalibrated time during one or more of the following conditions: engine not running, engine coolant temperature is greater than 255°F (124°C), A/C refrigerant pressure less than 38 psi (2.7 kg/cm 2 ) or greater than 429 psi (30.2 kg/cm 2 ), or Diagnostic Trouble Code (DTC) 66 or 70 is present and no A/C request signal exists from A/C select switch or circuit.

Scheme 1

Scheme 1: CHART C-10 - A/C COMPRESSOR CLUTCH CIRCUIT DIAGNOSIS
Scheme 1: CHART C-10 - A/C COMPRESSOR CLUTCH CIRCUIT DIAGNOSIS

Note. Test numbers refer to numbers on diagnostic chart. (Scheme 2)

Scheme 2

Scheme 2
Scheme 2
  1. If DTCs are present, see the «TESTS W/CODES - 3.1L»(/chevrolet/lumina/i-1989-2001/remont/testing-diagnostics/#engine-controls-tests-wcodes-31l) article in the ENGINE PERFORMANCE section. PCM will energize A/C relay only when engine is running. This test determines whether relay or circuit No. 459 is faulty.
  2. Determines if signal is reaching PCM through circuit No. 66 from A/C control panel. Signal should only be present when A/C mode or defrost mode is selected. NOTE: Test numbers refer to numbers on diagnostic chart. (Scheme 3)
  3. Determines if A/C refrigerant pressure sensor is out-of-range, causing compressor clutch to disengage.
  4. With engine stopped and A/C relay output test activated, PCM should ground circuit No. 459, causing test light to come on.

Scheme 3

Scheme 3
Scheme 3

Diagnostic Aids

Check branch circuits and splices to other components. If complaint is insufficient cooling, problem may be caused by an inoperative cooling fan. See appropriate C-12 chart in the ENGINE COOLING FAN article in the ENGINE COOLING section. If cooling fan operates correctly, problem is a basic A/C system problem.

PCM will disable A/C compressor if refrigerant pressure is not 38-429 psi (2.7-30.2 kg/cm 2 ). If refrigerant pressure is okay, check A/C pressure sensor circuit. If A/C pressure sensor circuit is okay, replace A/C pressure sensor.

3.4L - VIN X (EXCEPT REGAL)

A/C compressor clutch relay is controlled by the Powertrain Control Module (PCM). The PCM provides a ground on circuit No. 459 and A/C is requested. PCM will delay A/C compressor clutch engagement momentarily after A/C is requested. This delay allows Idle Air Control (IAC) valve to adjust engine RPM for additional load.

PCM will temporarily disengage A/C compressor clutch for a precalibrated time during one or more of the following conditions: engine not running, engine coolant temperature is greater than 255°F (124°C), A/C refrigerant pressure is less than 38 psi (2.7 kg/cm 2 ) or greater than 436 psi (30.6 kg/cm 2 ) or if Diagnostic Trouble Code (DTC) P1530 is set.

Scheme 4

Scheme 4: CHART C-10 - A/C COMPRESSOR CLUTCH CIRCUIT DIAGNOSIS
Scheme 4: CHART C-10 - A/C COMPRESSOR CLUTCH CIRCUIT DIAGNOSIS

Note. Test numbers refer to numbers on diagnostic chart. (Scheme 5)

Scheme 5

Scheme 5
Scheme 5

Scheme 6

Scheme 6
Scheme 6
  1. Checks for A/C clutch operation with A/C control head in OFF position.
  2. Determines if signal is reaching PCM through circuit No. 66 from A/C control panel. Signal should only be present when A/C mode or defrost mode is selected.
  3. Determines if A/C refrigerant pressure sensor is out-of-range, causing compressor clutch to disengage. NOTE: Test numbers refer to numbers on diagnostic chart. (Scheme 6)
  4. Bypasses A/C compressor clutch relay and PCM control circuit.
  5. Checks for voltage on circuit No. 739 to terminal F8.
  6. Determines if voltage and ground are present to energize A/C compressor clutch relay.
  7. With fused jumper installed, voltage should be present at A/C compressor clutch connector terminal "B".
  8. Checks for ground at A/C compressor clutch connector terminal "A". NOTE: Test numbers refer to numbers on diagnostic chart. (Scheme 7)
  9. Determines if PCM is commanding A/C compressor clutch on.
  10. Determines if circuit No. 66 is requesting PCM to energize A/C compressor clutch relay.
  11. Eliminates A/C compressor clutch relay and PCM control circuit.
  12. Checks for grounded circuit No. 459.

Scheme 7

Scheme 7
Scheme 7

Check branch circuits and splices to other components. If complaint is insufficient cooling, problem may be caused by an inoperative cooling fan. See appropriate C-12 chart in the ENGINE COOLING FAN article in the ENGINE COOLING section. If cooling fan operates correctly, problem is a basic A/C system problem.

PCM will disable A/C compressor if refrigerant pressure is not 38-436 psi (2.7-30.6 kg/cm 2 ). If refrigerant pressure is okay, check A/C pressure sensor circuit. If A/C pressure sensor circuit is okay, replace A/C pressure sensor.

3.8L - VIN L (REGAL)

A/C compressor clutch relay is controlled by the Powertrain Control Module (PCM). The PCM provides a ground on circuit No. 459 and A/C is requested. PCM will delay A/C compressor clutch engagement momentarily after A/C is requested. This delay allows Idle Air Control (IAC) valve to adjust engine RPM for additional load.

PCM will temporarily disengage A/C compressor clutch for a precalibrated time during one or more of following conditions: Wide Open Throttle (WOT), engine coolant temperature greater than 250°F (121°C) or engine RPM greater than 4800 RPM.

Scheme 8

Scheme 8: CHART C-10 - A/C COMPRESSOR CLUTCH CIRCUIT DIAGNOSIS
Scheme 8: CHART C-10 - A/C COMPRESSOR CLUTCH CIRCUIT DIAGNOSIS

Note. Test numbers refer to numbers on diagnostic chart. (Scheme 9)

Scheme 9

Scheme 9
Scheme 9

Scheme 10

Scheme 10
Scheme 10
  1. A/C clutch should not engage with engine running if an A/C mode is not selected at control head.
  2. Compressor clutch should apply if intake air temperature is greater than 60°F (15.5°C) or engine coolant temperature is less than 246°F (119°C).
  3. Checks for an A/C request signal from control head to PCM.
  4. Checks for an A/C request signal to A/C high pressure cut-out switch. NOTE: Test numbers refer to numbers on diagnostic chart. (Scheme 10)
  5. Checks for ignition voltage on circuit No. 739 and PCM control of ground circuit No. 459 to A/C relay coil.
  6. Checks for ignition voltage on circuit No. 739 to A/C relay contacts.
  7. Determines whether A/C relay, compressor clutch coil or circuitry is at fault. NOTE: Test numbers refer to numbers on diagnostic chart. (Scheme 11)
  8. Determines if PCM is turning on A/C relay due to false A/C request.
  9. Determines whether problem is in A/C control head and circuits No. 66 and 257 to pressure cycling switch, or circuit No. 67 and PCM.
  10. Checks for short to battery voltage in circuit No. 59 or faulty compressor clutch.
  11. Determines if A/C relay is faulty or A/C relay control circuit No. 459 is grounded at all times.

Scheme 11

Scheme 11
Scheme 11