Inspection Procedure 6
INSPECTION PROCEDURE 6: When the A/C is Operating, Temperature Inside the Passenger Compartment does not Decrease (Cool Air is not Emitted).
PROBABLE CAUSES
- Improper amount of refrigerant
- Malfunction of the A/C-ECU
DIAGNOSIS
Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra Fine Probe
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A
STEP 1. Using scan tool MB991958, read the diagnostic trouble code.
CAUTION:
To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK"
(OFF) position before connecting or disconnecting scan tool MB991958.
Check if an A/C-ECU DTC is set.
(1)Connect scan tool MB991958 to the data link connector.
(2)Turn the ignition switch to the "ON" position.
(3)Check if the DTC is set.
(4)Turn the ignition switch to the "LOCK" (OFF) position.
Q. Is the check result satisfactory?
YES Refer to Diagnostic Trouble Code Chart Automatic Air Conditioning.
NO Go to Step 2.
STEP 2. Using scan tool MB991958 read the ECM [M/T] or PCM [A/T] diagnostic trouble code.
Check whether engine or automatic transaxle DTCs are set or not.
(1)Turn the ignition switch to the "ON" position.
(2)Check for engine and automatic transaxle DTCs.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
Q. Is the check result satisfactory?
YES Go to Step 3.
NO Diagnose the ECM [M/T] or PCM [A/T] Multiport Fuel Injection (MFI) [3.8L ENGINE]).
STEP 3. Using scan tool MB991958, check actuator test.
(1)Connect scan tool MB991958 to the data link connector.
(2)Start the engine.
(3)Use scan tool MB991958 to run the actuator test.
- Item 77: Condenser fan: 0%
- Item 78: Condenser fan: 100%
- Item 79: Condenser fan: 50%
- Check that the condenser motor operates.
(4)Turn the ignition switch to the "LOCK" (OFF) position.
Q. Does the motor operate normally?
YES Go to Step 4.
NO Refer to Inspection procedure 9, "The condenser fan and the radiator fan do not operate ."
STEP 4. Check the A/C compressor operation.
Does the A/C compressor operate?
Q. Is the check result satisfactory?
YES Go to Step 5.
NO Refer to Inspection procedure 10, "The compressor does not work Inspection Procedure 3."
STEP 5. Using scan tool MB991958, check actuator test.
(1)Connect scan tool MB991958 to the data link connector.
(2)Start the engine.
(3)Use scan tool MB991958 to run the actuator test.
Item 42: air mix damper motor 0% (MAX COOL position)
Item 43: air mix damper motor 100% (MAX HOT position)
Item 44: air mix damper motor 50% (middle position)
- Check that the air mixing damper control motor operates.
(4)Turn the ignition switch to the "LOCK" (OFF) position.
Q. Does the motor operate normally?
YES Go to Step 7.
NO Go to Step 6.
STEP 6. Retest the system.
Check the trouble symptom again.
Q. Is the check result satisfactory?
YES It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.
NO Replace the A/C-ECU.
STEP 7. Check the refrigerant level.
Refer to Sight Glass Refrigerant Level Test.
Q. Is the check result satisfactory?
YES Go to Step 8.
NO Replenish the refrigerant.
STEP 8. Retest the system.
Check the trouble symptom again.
Q. Is the check result satisfactory?
YES It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.
NO Replace the A/C-ECU.