AC(diag)-20
Diagnostics for A/C System Malfunction
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
7
CHECK A/C ON SIGNAL.
1) Turn the ignition switch to OFF.
2) Connect the A/C relay and all disconnected
connectors.
3) Start the engine and turn the AUTO switch
to ON.
4) Turn the temperature control dial at maxi-
mum cool position.
5) Measure the voltage between auto A/C con-
trol module harness connector terminal and
chassis ground.
Connector & terminal
(B282) No. 15 (+) — Chassis ground (–):
Is the voltage 5.5 V or more?
Go to step 9.
Go to step 8.
8
CHECK HARNESS BETWEEN AUTO A/C
CONTROL MODULE AND ECM.
1) Turn the ignition switch to OFF.
2) Disconnect the harness connector of auto
A/C control module and ECM.
3) Measure the resistance of harness between
auto A/C control module connector and ECM
connector.
Connector & terminal
(B282) No. 15 — (B136) No. 24:
Is the resistance less than 1
:? Replace the auto
A/C control mod-
ule.
Repair the har-
ness.
9
CHECK MAGNET CLUTCH ON SIGNAL.
1) Stop the engine, and turn the AUTO switch
to OFF.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM connec-
tor terminal and chassis ground.
Connector & terminal
(B136) No. 9 (+) — Chassis ground (–):
Is the voltage 10 V or more?
Go to step 10.
Check for open or
short circuit in the
harness between
A/C relay and
ECM.
10
CHECK MAGNET CLUTCH ON SIGNAL.
1) Start the engine and turn the AUTO switch
to ON.
2) Turn the temperature control dial at maxi-
mum cool position.
3) Measure the voltage between ECM connec-
tor terminal and chassis ground.
Connector & terminal
(B136) No. 9 (+) — Chassis ground (–):
Is the voltage 0 V?
Go to step 11.
Replace the ECM.
11
CHECK POWER SUPPLY FOR MAGNET
CLUTCH.
1) Stop the engine, and turn the AUTO switch
to OFF.
2) Disconnect the harness connector of mag-
net clutch.
3) Start the engine and turn the AUTO switch
to ON.
4) Turn the temperature control dial at maxi-
mum cool position.
5) Measure the voltage between magnet
clutch harness connector terminal and chassis
ground.
Connector & terminal
(F24) No. 1 (+) — Chassis ground (–):
Is the voltage 10 V or more?
Go to step 12.
Check for open or
short circuit in the
harness between
A/C relay and mag-
net clutch.
Step
Check
Yes
No