AC(diag)-21
Diagnostics for A/C System Malfunction
HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)
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
(i88) No. 36 — (B136) No. 29:
Is the resistance less than 1 Ω? Go to step
9.
Repair the har-
ness.
9
CHECK MAGNET CLUTCH ON SIGNAL.
1) Stop the engine and turn the A/C switch to
OFF.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM connec-
tor terminal and chassis ground.
Connector & terminal
(B135) No. 35 (+) — 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 A/C 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
(B135) No. 35 (+) — Chassis ground (–):
Is the voltage 0 V?
Go to step
11.
Replace the ECM.
<Ref. to FU(STI)-
59, REMOVAL,
Engine Control
Module (ECM).>
<Ref. to FU(w/o
STI)-57,
REMOVAL, Engine
Control Module
(ECM).>
11
CHECK POWER SUPPLY FOR MAGNET
CLUTCH.
1) Stop the engine and turn the A/C switch to
OFF.
2) Disconnect the harness connector of mag-
net clutch.
3) Start the engine and turn the A/C 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?
Inspect the com-
pressor. <Ref. to
AC-33, INSPEC-
TION, Compres-
sor.>
Check for open or
short circuit in the
harness between
A/C relay and mag-
net clutch.
Step
Check
Yes
No