A/C Load Signal System - Mitsubishi Electric Lancer Evolution-VII Workshop Manual

Inspection Procedure 28

A/C load signal system

The size of the A/C compressor load is detected according to the difference in
set temperature. When the A/C large load signal is input to the engine-ECU, the
engine-ECU judges that the A/C compressor load is large, and controls the
throttle valve control servo so that the idling speed increases.
Measure at the C-126 engine-ECU
connector.
D Measure the engine-ECU terminal
voltage.
D Engine: Idling
D A/C switch: ON
(A/C compressor driven state)
D Voltage between terminal No. 24
and earth
D A/C setting temperature: Minimum
temperature
Air volume: Maximum
Outdoor air sensor ambient
temperature: 18_C or more
OK: 1 V or less
D A/C setting temperature: indoor
temperature
Air volume: Minimum
OK: System voltage
OK
Check the following connector: C-126
OK
Measure at the C-32 A/C-ECU
connector <manual A/C> or C-30
A/C-ECU connector <automatic
A/C>.
D Measure the A/C-ECU terminal
voltage.
D Engine: Idling
D A/C setting temperature: Minimum
temperature
When room temperature is 25_
or more: Max Cool
When room temperature is 25_
or less: Max. Hot
D A/C switch: ON
D Voltage between terminal No. 2
and earth <manual A/C (R.H.
drive vehicles)>
D Voltage between terminal No. 5
and earth <manual A/C (L.H.
drive vehicles)>
D Voltage between terminal No. 32
and earth <automatic A/C>
OK: System voltage
OK
Check the following connectors:
C-32 <manual A/C> ,
C-30 <automatic A/C>, C-128 <R.H.
drive vehicles>, C-130 <L.H. drive
vehicles>
OK
Check and repair the harness
between the engine-ECU and
A/C-ECU.
D Check for disconnection of the
output cable.
MPI -
Troubleshooting
NG
Check the following connector: C-126
Check the trouble symptoms.
Replace the engine - ECU.
NG
Repair
NG
Check the following connectors:
C-16 <manual A/C> ,
C-18 <automatic A/C>, C-20
Check the harness between the
engine-ECU and A/C-ECU.
D Check for short-circuit of the
output cable.
Check the A/C system.
(Refer to GROUP 55 -
Troubleshooting.)
NG
Repair
Probable cause
D A/C-ECU malfunction
D Engine-ECU malfunction
NG
OK
OK
NG
NG
OK
NG
OK
13A-95
Repair
Intermittent malfunction (Refer to
GROUP 00 - Points to Note for
Intermittent Malfunctions.)
Repair
Repair