Page 1905 of 2267

Diagnostic Procedure 2: Models with relay
type 2
SYMPTOM: Blower motor does not rotate at all when the fan
speed is in AUTO. (It operates in 1, 2, 3, or
4-speed only.)
CHECK POWER SUPPLY FOR A/C
(LO) RELAY.
Disconnect LO relay harness connec-
tor.
Do approx.12 voltsexist between
AUTO relay harness terminal No.
p1
and body ground?
OK
ENG
Check 10A fuse (No.26)
at fuse block.
(Refer to ªPOWER SUP-
PLY ROUTINGº in EL sec-
tion and Wiring Diagram.)
Check circuit continuity between LO
relay harness terminal No.
p2and
body ground.
OK
ENG
CHECK FAN SWITCH
(Refer to Electrical Com-
ponents Inspection.)
(HA-78)
OK NG
Replace
A/C con-
trol panel.
Note
Check circuit continuity
between LO relay har-
ness terminal No.
p2
and A/C control panel
harness terminal No.
p33.
Note
CHECK POWER SUPPLY FOR LO
RELAY.
Do approx.12 voltsexist between LO
relay harness terminal No.
p3and
body ground?
OK
ENG
Check circuit continuity
between resistor harness
terminal No.
p8and LO
relay harness terminal
No.
p3.
pA
(Go to next page.)
Note:
If the result is NG or No after checking circuit continuity, repair harness or
connector.
YHA379
YHA380
YHA381
YHA382
YHA389
H
H
H
H
H
TROUBLE DIAGNOSESAUTO
HA-56
Page 1906 of 2267

pA
Note
Check circuit continuity between LO relay
harness terminal No.
p5and body ground.
OK
CHECK LO RELAY AFTER DISCON-
NECTING IT.
ENG
Replace LO relay.
Diagnostic Procedure 3: Models with relay
type 1
SYMPTOM: Blower motor fan speed does not change when
fan speed is in AUTO. (Fan speed is fixed in
HIGH or MED.)
C/R*1Note
CHECK AUTO AMP. AND PTC.
Connect checking resistor.
(Refer to HA-51.)
Does blower motor fan speed change
when you move PTC from 18ÉC (64ÉF)
to 32ÉC (90ÉF)?
OK
ENG
CHECK PTC CIRCUIT
BETWEEN CONTROL
PANEL AND AUTO
AMP.
Disconnect control panel
and auto amp. harness
connectors.
Check circuit continuity
between control panel
harness terminal No.
p21and auto amp. har-
ness terminal No.
p4.
OK
CHECK SENSOR CIRCUIT.
Note
Check circuit continuity
between control panel
harness terminal No.
p25and auto amp. har-
ness terminal No.
p5.
OK
Reconnect control panel harness con-
nector.
FOK
CHECK A/C CONTROL
PANEL.
(Refer to HA-51.)
NG
Replace A/C Control
panel.
pA
(Go to next page.)
Note:
If the result is NG or No after checking circuit continuity, repair harness or
connector.
How to repair
Ambient sensor
circuitGo to Diagnostic
Procedure 11.
In-vehicle sensor
circuitGo to Diagnostic
Procedure 12.
YHA384
YHA262
Control panel
connectorAuto amp.
connector
YHA263
Auto amp.
connectorControl panel
connector
H
H
HH
H
H
H
TROUBLE DIAGNOSESAUTO
Diagnostic Procedure 2: Models with relay
type 2 (Cont'd)
HA-57
Page 1907 of 2267
pA
CHECK AUTO AMP.
Connect checking resistor.
(Refer to HA-30.)
Do approx.12 voltsexist between auto
amp. harness terminal No.
p15,p16
and body ground?
OK
ENG
Replace auto amp.
CHECK HIGH OR MED-HIGH, MED-
LOW RELAY AFTER DISCONNECT-
ING IT. (Refer to HA-78.)
OK
ENG
Replace HIGH relay or
MED-HIGH, MED-LOW
relay.
Note
Does continuity exist between blower
motor harness terminal No.
p2and
HIGH relay terminal No.
p3?
Ye s
Note
Does continuity exist between resistor
harness terminal No.
p6and MED-
HIGH relay harness terminal No.
p3?
Ye s
Replace auto amp.
Note:
If the result is NG or No after checking circuit continuity, repair harness or
connector.
NHA301
Auto amp. connector
Checking resistor
Refer to pageHA-30.
NHA449
Blower motor
connectorHIGH relay
connector
YHA253
Fan resistor
connectorMED-HIGH Relay
connector
H
H
H
H
H
TROUBLE DIAGNOSESAUTO
Diagnostic Procedure 3: Models with relay
type 1 (Cont'd)
HA-58
Page 1908 of 2267

Diagnostic Procedure 3: Models with relay
type 2
SYMPTOM: Blower motor fan speed does not change when
fan speed is in AUTO. (Fan speed is fixed in
HIGH or MED.)
C/R*1Note
CHECK AUTO AMP. AND PTC.
Connect checking resistor.
(Refer to HA-51.)
Does blower motor fan speed change
when you move PTC from 18ÉC (64ÉF)
to 32ÉC (90ÉF)?
OK
ENG
CHECK PTC CIRCUIT
BETWEEN CONTROL
PANEL AND AUTO
AMP.
Disconnect control panel
and auto amp. harness
connectors.
Check circuit continuity
between control panel
harness terminal No.
p21and auto amp. har-
ness terminal No.
p4.
OK
CHECK SENSOR CIRCUIT.
Note
Check circuit continuity
between control panel
harness terminal No.
p25and auto amp. har-
ness terminal No.
p5.
OK
Reconnect control panel harness con-
nector.
FOK
CHECK A/C CONTROL
PANEL.
(Refer to HA-51.)
NG
Replace A/C Control
panel.
pA
(Go to next page.)
Note:
If the result is NG or No after checking circuit continuity, repair harness or
connector.
How to repair
Ambient sensor
circuitGo to Diagnostic
Procedure 11.
In-vehicle sensor
circuitGo to Diagnostic
Procedure 12.
YHA262
Control panel
connectorAuto amp.
connector
YHA263
Auto amp.
connectorControl panel
connector
HH
H
H
H
TROUBLE DIAGNOSESAUTO
HA-59
Page 1909 of 2267
pA
CHECK AUTO AMP.
Connect checking resistor.
(Refer to HA-30.)
Do approx.12 voltsexist between auto
amp. harness terminal No.
p15,p16
and body ground?
OK
ENG
Replace auto amp.
CHECK HIGH OR MED-HIGH, MED-
LOW RELAY AFTER DISCONNECT-
ING IT. (Refer to HA-78.)
OK
ENG
Replace HIGH relay or
MED-HIGH, MED-LOW
relay.
Note
Does continuity exist between blower
motor harness terminal No.
p2and
HIGH relay terminal No.
p3?
Ye s
Note
Does continuity exist between resistor
harness terminal No.
p6and MED-
HIGH relay harness terminal No.
p3?
Ye s
Replace auto amp.
Note:
If the result is NG or No after checking circuit continuity, repair harness or
connector.
NHA301
Auto amp. connector
Checking resistor
Refer to pageHA-30.
NHA449
Blower motor
connectorHIGH relay
connector
YHA385
H
H
H
H
H
TROUBLE DIAGNOSESAUTO
Diagnostic Procedure 3: Models with relay
type 2 (Cont'd)
HA-60
Page 1910 of 2267

Diagnostic Procedure 4: Models with relay
type 1
SYMPTOM: Blower motor fan speed does not change when
fan speed is in AUTO. (Fan speed is fixed in
LOW.)
CHECK THERMAL TRANSMITTER.
Disconnect auto amp. harness connec-
tor.
Is resistance between auto amplifier
terminal No.
p10andp5lower than
approx.940W?
NG
EOK
CHECK POWER SUP-
PLY FOR LOW RELAY.
Disconnect low relay.
Do approx.12 voltsexist
between low relay har-
ness terminal No.
p1
and body ground?
OK
NG
CHECK THERMAL TRANSMITTER
CIRCUIT.
Go toDiagnostic Procedure 14.
(HA-77)
Reconnect low relay.Check 10A fuse (No.26)
at fuse block.
(Refer to ªPOWER SUP-
PLY ROUTINGº in EL sec-
tion and Wiring Diagram.)
CHECK A/C CONTROL PANEL
Do approx.0.5Vexist between A/C
control panel terminal
p35and body
ground when you select AUTO posi-
tion?
OK
ENG
Replace A/C control
panel.
Note
Check circuit continuity between A/C
control panel harness terminal
p35and
auto amp. harness terminal
p11.
OK
CHECK AUTO AMP.
Connect checking resistor.
(Refer to HA-30.)
Do approx.0 voltsexist between low
relay harness terminal No.
p2and
body ground when you move PTC
from 18ÉC (64ÉF) to 32ÉC (90ÉF)?
OK
ENG
Replace low relay.
pA
(Go to next page)
Note:
If the result is NG or No after checking circuit continuity, repair harness or
connector.
YHA254
Auto amp. connector
AUTO amp.
connector
YHA390
NHA450
A/C control panel
connector
YHA259
Auto amp.
connectorA/C control panel
connector
YHA391
H
HH
H
H
H
H
TROUBLE DIAGNOSESAUTO
HA-61
Page 1911 of 2267
pA
CHECK POWER SUPPLY FOR AUTO
AMP.
Disconnect auto amp. harness connec-
tor.
Do approx.12 voltsexist between auto
amp. harness terminal No.
p1and
body ground?
OK
ENG
Check 10A fuse (No.26)
at fuse block.
(Refer to ªPOWER SUP-
PLY ROUTINGº in EL sec-
tion and Wiring Diagram.)
Note
CHECK BODY GROUND CIRCUIT
FOR AUTO AMP.
Does continuity exist between auto
amp. harness terminal No.
p17and
body ground?
OK
Replace auto amp.
Note:
If the result is NG or No after checking circuit continuity, repair harness or
connector.
YHA257
Auto amp. connector
YHA258
Auto amp. connector
H
H
H
TROUBLE DIAGNOSESAUTO
Diagnostic Procedure 4: Models with relay
type 1 (Cont'd)
HA-62
Page 1912 of 2267

Diagnostic Procedure 4: Models with relay
type 2
SYMPTOM: Blower motor fan speed does not change when
fan speed is in AUTO. (Fan speed is fixed in
LOW.)
CHECK THERMAL TRANSMITTER.
Disconnect auto amp. harness connec-
tor.
Is resistance between auto amplifier
terminal No.
p10andp5lower than
approx.940W?
NG
EOK
CHECK POWER SUP-
PLY FOR LOW RELAY.
Disconnect low relay.
Do approx.12 voltsexist
between low relay har-
ness terminal No.
p1
and body ground?
OK
NG
CHECK THERMAL TRANSMITTER
CIRCUIT.
Go toDiagnostic Procedure 14.
(HA-77)
Reconnect low relay.Check 10A fuse (No.26)
at fuse block.
(Refer to ªPOWER SUP-
PLY ROUTINGº in EL sec-
tion and Wiring Diagram.)
CHECK A/C CONTROL PANEL
Do approx.0.5Vexist between A/C
control panel terminal
p35and body
ground when you select AUTO posi-
tion?
OK
ENG
Replace A/C control
panel.
Note
Check circuit continuity between A/C
control panel harness terminal
p35and
auto amp. harness terminal
p11.
OK
CHECK AUTO AMP.
Connect checking resistor.
(Refer to HA-30.)
Do approx.0 voltsexist between low
relay harness terminal No.
p2and
body ground when you move PTC
from 18ÉC (64ÉF) to 32ÉC (90ÉF)?
OK
ENG
Replace low relay.
pA
(Go to next page)
Note:
If the result is NG or No after checking circuit continuity, repair harness or
connector.
YHA254
Auto amp. connector
AUTO amp.
connector
YHA386
NHA450
A/C control panel
connector
YHA259
Auto amp.
connectorA/C control panel
connector
YHA387
H
HH
H
H
H
H
TROUBLE DIAGNOSESAUTO
HA-63