A/C Compressor Relay System - Mitsubishi Lancer Evolution-VII Workshop Manual

Inspection Procedure 27

A/C compressor relay system

When the A/C switch ON signal is input to the engine-ECU, the engine-ECU
turns the A/C compressor relay ON.
The A/C compressor magnetic clutch starts with this.
Check the following connector: B-12X
OK
Check the A/C compressor relay. (Refer to 55 - On-vehicle
service.)
OK
Measure at the B-12X A/C
compressor relay connector.
D Remove the relay, and measure
at the connector side.
(1) Voltage between terminal No. 2
and earth
(Ignition switch: ON)
OK: System voltage
(2) Voltage between terminal No. 1
and earth
OK: System voltage
OK
Check the following connector: A-47
OK
Measure at the A-47 A/C
compressor connector.
D Measure the engine-ECU terminal
voltage.
D Remove the B-12X A/C
compressor relay, and
short-circuit between the harness
connector's terminal No. 1 and
terminal No. 4.
D Ignition switch: ON
D Voltage between terminal No. 1
and earth
OK: System voltage
OK
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MPI -
Troubleshooting
NG
NG
(1) NG
Check the following connectors:
C-128 <R.H. drive vehicles>, C-130
<L.H. drive vehicles>, C-102, C-209,
C-210, C-201
Check and repair the harness
between the ignition switch and A/C
compressor relay.
D Check for disconnection and
short-circuit of the power cable.
(2) NG
Check the following connector:
C-136 <R.H. drive vehicles>, A-43
<L.H. drive vehicles>
Check and repair the harness
between the battery and A/C
compressor relay.
D Check for disconnection and
short-circuit of the power cable.
NG
Repair
NG
Check the following connector:
C-136 <R.H. drive vehicles>, A-43
<L.H. drive vehicles>
Check and repair the harness
between the A/C compressor relay
and A/C compressor.
D Check for disconnection and
short - circuit of the output cable.
Probable cause
D A/C compressor relay malfunction
D A/C compressor magnetic clutch malfunction
D Engine-ECU malfunction
Repair
Replace the A/C compressor relay.
NG
OK
NG
OK
NG
OK
13A-93
Repair
Repair
Repair