NO.8 NO COOL AIR


BHE070301038W10

8

No cool air

DESCRIPTION

• Magnetic clutch does not operate.

POSSIBLE CAUSE

• Malfunction in PCM A/C cut control system (Step 3)
• Malfunction in A/C amplifier (Step 4)
• Malfunction in refrigerant pressure switch (Steps 5, 7-9)
• Malfunction in PCM (A/C signal) (Step 6)
• Malfunction in PCM (IG1 signal) (Steps 10, 11)
• Malfunction in A/C compressor (Step 12)
• Malfunction in A/C relay (Steps 13-15)
• Malfunction in evaporator temperature sensor (Step 16)

• When performing an asterisked (*) troubleshooting inspection, shake the wiring harness and connectors while performing the inspection to discover whether poor contact points are the cause of any intermittent malfunctions. If there is a problem, check to make sure connectors, terminals and wiring harnesses are connected correctly and undamaged.

Diagnostic procedure

STEP

INSPECTION

ACTION

1

INSPECT AIR BLOW OUT

• Does air blow out?
Yes
Go to next step.
No
Go to Step 1 of troubleshooting indexes No.1 and 2.
2

INSPECT A/C COMPRESSOR OPERATION

• Start engine.
• Turn A/C switch and fan switch on.
• Does A/C compressor operate?
Yes
Go to Step 1 of troubleshooting index No.7.
No
Go to next step.
3

INSPECT FOR DTC IN PCM

• Inspect for DTCs related to the PCM on-board diagnostic system.
• Are any DTCs displayed?
Yes
Go to appropriate inspection procedure.
No
Go to next step.
4

INSPECT TO SEE WHETHER MALFUNCTION IS IN A/C AMPLIFIER OR ELSEWHERE

• Does cool air blow out when terminal 1M of A/C amplifier connector (24-pin, A/C signal) is grounded?
Yes
Replace A/C amplifier, then go to Step 17.
No
Release short, then go to next step.
5*

INSPECT TO SEE WHETHER MALFUNCTION IS IN A/C SIGNAL CIRCUIT (BETWEEN REFRIGERANT PRESSURE SWITCH AND PCM) OR ELSEWHERE

• Test voltage at the following terminal of refrigerant pressure switch:
– Terminal B (A/C signal)
• Is voltage approx. 12 V?
Yes
Go to Step 7.
No
Go to next step.
6*

INSPECT TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY) IS IN WIRING HARNESS (BETWEEN REFRIGERANT PRESSURE SWITCH AND PCM) OR PCM

• Test voltage at A/C signal terminal of PCM.
• Is voltage approx. 12 V?
Yes
Repair wiring harness between PCM and refrigerant pressure switch, then go to Step 17.
No
Inspect PCM, then go to Step 17. (See PCM INSPECTION.)
7

INSPECT TO SEE WHETHER MALFUNCTION IS IN REFRIGERANT PRESSURE SWITCH, REFRIGERANT AMOUNT, OR ELSEWHERE

• Does cool air blow out when terminals A and B of refrigerant pressure switch connector are shorted?
Yes
Go to Step 9.
No
Go to next step.
8*

INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (BETWEEN REFRIGERANT PRESSURE SWITCH AND A/C AMPLIFIER) OR ELSEWHERE

• Test voltage at the following terminal of A/C amplifier.
– Terminal 1M (24-pin, A/C signal)
• Is voltage approx. 12 V?
Yes
Go to Step 10.
No
Repair wiring harness between refrigerant pressure switch and A/C amplifier, then go to Step 17.
9

INSPECT TO SEE WHETHER MALFUNCTION IS IN REFRIGERANT PRESSURE SWITCH OR REFRIGERANT AMOUNT

• Inspect refrigerant pressure switch.
• Is it normal?
Yes
If there is no refrigerant, replace condenser, bleed the refrigerant line for 30 min or more using a vacuum pump, and add refrigerant to specified level, then go to Step 17.
No
Replace refrigerant pressure switch, then go to Step 17. (See REFRIGERANT PRESSURE SWITCH REMOVAL/INSTALLATION.)
10

INSPECT TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY) IS IN A/C CONTROL SIGNAL CIRCUIT (BETWEEN A/C RELAY AND PCM) OR ELSEWHERE

• Does cool air blow out when terminal E of A/C relay connector (A/C control signal) is grounded?
Yes
Release short, then go to next step.
No
Go to Step 12.
11*

INSPECT TO SEE WHETHER MALFUNCTION (LACK OF CONTINUITY) IS IN PCM OR WIRING HARNESS (BETWEEN A/C RELAY AND PCM)

• Test voltage at the A/C relay control signal terminal of PCM.
• Is voltage approx. 12 V?
Yes
Inspect PCM, then go to Step 17.
No
Repair wiring harness between A/C relay and PCM, then go to Step 17.
12*

INSPECT TO SEE WHETHER MALFUNCTION IS IN MAGNETIC CLUTCH OR ELSEWHERE

• Test voltage at the following terminal of magnetic clutch thermal protector:
– Terminal B (magnetic clutch operation signal)
• Is voltage approx. 12 V?
Yes
Inspect magnetic clutch, then go to Step 17. (See MAGNETIC CLUTCH INSPECTION.)
No
Go to next step.
13

INSPECT FUSE

• Are A/C relay power supply fuses normal?
Yes
Go to next step.
No
Replace fuse, then go to Step 17. If fuse burns out immediately, go to next step.
14

INSPECT WIRING HARNESS BETWEEN FUSE BLOCK AND A/C RELAY FOR LACK OF CONTINUITY

• Test voltages at the following terminals of A/C relay.
– Terminal A (A/C relay control signal)
– Terminal C (A/C control signal)
• Are voltages approx. 12 V?
Yes
Go to next step.
No
Repair wiring harness between fuse block and A/C relay, then go to Step 17.
15

INSPECT TO SEE WHETHER MALFUNCTION IS IN A/C RELAY OR WIRING HARNESS (BETWEEN A/C RELAY AND MAGNETIC CLUTCH) AND EVAPORATOR TEMPERATURE SENSOR

• Test voltage at the following terminal of A/C relay:
– Terminal D (magnetic clutch operation signal)
• Is voltage approx. 12 V?
Yes
Inspect wiring harness between A/C relay and magnetic clutch.
• If above wiring harness is normal, go to next step.
• If above wiring harness malfunctions, repair wiring harness, then go to Step 17.
No
Replace A/C relay, then go to Step 17.
16

INSPECT EVAPORATOR TEMPERATURE SENSOR

• Inspect evaporator temperature sensor.
• Is it normal?
Yes
Go to next step.
No
Replace evaporator temperature sensor, then go to next step. (See EVAPORATOR TEMPERATURE SENSOR REMOVAL/INSTALLATION.)
17

CONFIRM THAT MALFUNCTION SYMPTOMS DO NOT RECUR AFTER REPAIR

• Does cool air blow out? (Are the results of refrigerant system performance test normal?)
Yes
Troubleshooting completed. Explain repairs to customer.
No
Recheck malfunction symptoms, then repeat from Step 1 if malfunction recurs.