Diagnostic Aids
The Mitsubishi scroll type A/C compressor carries an internal thermal cut off switch. The thermal cut off switch normal operation is to open and disable the compressor under extreme load and temperatures above 155°C (311°F). The internal thermal cut off switch is non-serviceable.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Placing the mode switch in any position other than OFF, along with placing the air temperature control switch in a cold setting, activates A/C operation. For the purpose of this and future steps where A/C operation is necessary, bi-level mode is used for consistent testing.
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The HVAC control assembly is inoperative when the module does not respond to any operator control requests to enable the A/C compressor. The blower motor may still operate independent of the A/C controls.
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The A/C compressor relay output is disabled if engine coolant temperature is above 121°C (250°F) for the LX5 and 126°C (259°F) for the L47.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views DEFINITION: The A/C compressor clutch will not engage when an A/C request has been made and a Powertrain DTC has not been set. | |||
1 | Did you perform the HVAC Diagnostic System Check? | Go to Step 2 | |
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Important: : Ambient air temperature must be above 3°C (38°F).
Does the A/C compressor operate? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |
3 |
Are the low and high side pressure values within the allowable limits for the recorded ambient air temperature, and within 103 kPa (15 psi) of each other? | Go to Step 4 | Go to Leak Testing in Heating, Ventilation and Air Conditioning |
4 |
Are the high side pressure values with 103 kPa (15 psi) of each other? | Go to Step 5 | Go to Step 20 |
Is the HVAC control module inoperative? | Go to Step 19 | Go to Step 6 | |
6 |
Does the scan tool indicate that the A/C Relay Command parameter is ON? | Go to Step 13 | Go to Step 7 |
7 | With a scan tool, observe the A/C Clutch (desired) parameter in the DIM A/C Information list. Does the scan tool indicate that the A/C Clutch (desired) parameter is ON? | Go to Step 8 | Go to Step 9 |
8 | With a scan tool, observe the A/C Clutch (actual) parameter in the DIM A/C Information list. Does the scan tool indicate that the A/C Clutch (actual) parameter is ON? | Go to Step 13 | Go to Step 34 |
9 | With a scan tool, observe the Control Head (desired) parameter in the DIM A/C Information list. Does the scan tool indicate that the Control Head (desired) parameter is A/C ON? | Go to Step 10 | Go to Step 12 |
10 | With a scan tool, observe the Pressure Status parameter in the DIM A/C Information list. Does the scan tool indicate that the Pressure Status parameter is Normal? | Go to Step 11 | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems |
With a scan tool, observe the Temperature Status parameter in the DIM A/C Information list. Does the scan tool indicate that the Temperature Status parameter is OK? | Go to Step 31 | Go to Engine Overheating in Engine Cooling | |
12 |
Does the scan tool indicate that the Control Head (desired) parameter turn A/C ON and A/C OFF with each command? | Go to Step 30 | Go to Step 33 |
13 | With a scan tool, command the A/C Relay ON and OFF. Does the A/C compressor clutch relay turn ON and OFF with each command? | Go to Step 17 | Go to Step 14 |
14 |
Does the test lamp illuminate? | Go to Step 15 | Go to Step 27 |
15 |
Does the test lamp turn ON and OFF with each command? | Go to Step 29 | Go to Step 16 |
16 | Does the test lamp remain illuminated with each command? | Go to Step 23 | Go to Step 22 |
17 |
Does the test lamp illuminate? | Go to Step 18 | Go to Step 26 |
18 | Connect a 10-amp fused jumper wire between the switch side voltage circuit of the A/C compressor clutch relay and the A/C compressor clutch supply voltage circuit of the A/C compressor clutch. Does the A/C compressor clutch engage? | Go to Step 29 | Go to Step 24 |
19 | Test the ignition 3 voltage circuit of the HVAC control module for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 42 | Go to Step 21 |
20 | Test the low reference circuit of the A/C refrigerant pressure sensor for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 42 | Go to Step 28 |
21 | Test the ground circuit of the HVAC control module for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 42 | Go to Step 33 |
22 | Test the A/C compressor clutch relay control circuit of the A/C compressor clutch relay for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 42 | Go to Step 34 |
23 | Test the A/C compressor clutch relay control circuit of the A/C compressor clutch relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 42 | Go to Step 34 |
24 | Test the A/C compressor clutch supply voltage circuit at the A/C compressor clutch for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 42 | Go to Step 25 |
25 | Test the ground circuit of the A/C compressor clutch for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 42 | Go to Step 32 |
26 | Repair the switch side voltage supply circuit of the A/C compressor clutch relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 42 | -- |
27 | Repair the coil side voltage supply circuit of the A/C compressor clutch relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 42 | -- |
28 | Inspect for poor connections at the harness connector of the A/C refrigerant pressure sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 42 | Go to Step 37 |
29 | Inspect for poor connections at the A/C compressor clutch relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 42 | Go to Step 38 |
30 | Inspect for poor connections at the instrument panel integration module (IPM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 42 | Go to Step 35 |
31 | Inspect for poor connections at the dash integration module (DIM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 42 | Go to Step 36 |
32 | Inspect for poor connections at the harness connector of the A/C compressor clutch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 42 | Go to Step 39 |
33 | Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 42 | Go to Step 40 |
34 | Inspect for poor connections at the harness connector of the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 42 | Go to Step 41 |
35 | Replace the IPM. Refer to Instrument Panel Module Replacement in Body Control System. Did you complete the replacement? | Go to Step 42 | -- |
36 | Replace the DIM. Refer to Dash Integration Module Replacement in Body Control System. Did you complete the replacement? | Go to Step 42 | -- |
37 | Replace the A/C refrigerant pressure switch. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement in Heating, Ventilation and Air Conditioning. Did you complete the replacement? | Go to Step 42 | -- |
38 | Replace the A/C compressor clutch relay. Did you complete the replacement? | Go to Step 42 | -- |
39 | Replace the A/C compressor. Refer to Air Conditioning Compressor Replacement in Heating, Ventilation and Air Conditioning. Did you complete the replacement? | Go to Step 42 | -- |
40 | Replace the HVAC control module. Refer to HVAC Control Module Replacement . Did you complete the replacement? | Go to Step 42 | -- |
41 |
Important: Perform the programming procedure for the PCM. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls-4.0L. Did you complete the replacement? | Go to Step 42 | -- |
42 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
