Step
| Action
| Value(s)
| Yes
| No
|
1
| Are any HVAC DTCs or PCM DTCs stored?
| --
| For HVAC DTCs, Go to
DTC Table
For PCM DTCs, Go to
Diagnostic Trouble Code (DTC) List
| Go to
Step 2
|
2
|
- Inspect the outer surface of the condenser for items that may
restrict the air flow. Remove the following items as necessary:
- Inspect the area between the condenser and the radiator for tems
that may restrict air flow. Remove the following items as necessary:
- Inspect the condenser and the refrigerant lines or hoses for the
following conditions. Replace damaged components by following the instructions
found later in this section:
- With the A/C compressor operating, compare the clutch hub speed
to the pulley speed. If clutch slippage is indicated, replace the clutch.
Refer to Compressor Clutch Plate and Hub Assembly Removal (V5 - Conventional Mount)
.
- Select the A/C mode.
- With the engine idling and the A/C compressor operating, inspect
the engine cooling fan operation.
Is the left cooling fan operating at low speed and is the right cooling
fan operating at high speed?
| --
| Go to
Step 3
| Go to
Functional Check
|
3
|
- Verify that the ambient temperature is not less than the specified
value.
- Idle the engine at normal operating temperature.
- Open the hood and all of the body doors.
- Select the AUTO mode (CJ2).
- Set the temperature control to the MAX COLD position.
- Set the blower control to the HIGH position.
- Feel the condenser outlet in front of the expansion (orifice)
tube.
Does the condenser outlet feel warm?
| 21°C (70°F)
| Go to
Step 5
| Go to
Step 4
|
4
| A restriction exists in the high
side of the system.
- Inspect for frost in order to locate the restriction.
- Recover the refrigerant. Refer to Refrigerant Recovery and Recharging
.
- Repair as required.
- Recharge the A/C system. Refer to Refrigerant Recovery and Recharging
.
Did you complete the repair?
| --
| System OK
| --
|
5
|
• | Feel the evaporator inlet pipe. |
• | Feel the accumulator surface. |
Does the evaporator inlet pipe feel noticeably colder than the accumulator
surface?
| --
| Go to
Step 6
| Go to
Step 8
|
6
| A low
refrigerant charge is indicated.
Perform a leak test of the A/C system. Refer to
Leak Testing
.
Did you find and correct a leak?
| --
| Go to
Step 7
| Go to
Step 8
|
7
|
- Recover the refrigerant. Refer to Refrigerant Recovery and Recharging
.
- Repair as required.
- Recharge the A/C system. Refer to Refrigerant Recovery and Recharging
.
Is the repair complete?
| --
| System OK
| --
|
8
|
- Install the J 39500-B
to monitor the A/C system high-side and low-side pressures.
- Observe the low-side pressure gage.
Do the following actions occur?
• | The compressor turns OFF when the pressure drops to nearly the
minimum specified value. |
• | The compressor turn ON again when the pressure rises to nearly
the maximum specified value. |
| Minimum: 69 kPa (10 psi)
Maximum: 138 kPa (20 psi)
| Go to
Step 14
| Go to
Step 9
|
9
| Inspect the compressor.
Does the compressor run continuously?
| --
| Go to
Step 11
| Go to
Step 10
|
10
| The compressor cycles low or high.
Replace the faulty pressure recycling switch.
Is the repair complete?
| --
| System OK
| --
|
11
|
- Disconnect the blower motor connector.
- Observe the following components:
• | The low-side pressure gage |
• | The A/C compressor clutch |
Does the A/C compressor run continuously while the low-side pressure
drops below the specified value?
| 69 kPa (10 psi)
| Go to
Step 12
| Go to
Step 13
|
12
| Replace the faulty pressure cycling
switch.
Is the repair complete?
| --
| Go to
Step 14
| --
|
13
|
- One of the following conditions exists:
• | The compressor shuts off when the pressure drops to 138 kPa
(20 psi). |
• | The pressure never drops to 69 kPa (10 psi) and
the A/C compressor runs continuously. |
- Reconnect the blower motor.
Is the blower motor reconnected?
| --
| Go to
Step 14
| --
|
14
|
- Record the ambient temperature and the relative humidity.
- Select the AUTO mode.
- Set the temperature control to the MAX COLD position.
- Set the blower control to the HIGH position.
- Close all of the windows and the doors of the vehicle.
- Run the engine at idle.
- Install a thermometer in the vehicle A/C outlet. Wait for 10 minutes.
- Verify the system performance. Refer to
System Performance Test
.
Is the A/C outlet temperature within specified limits?
| --
| Go to
Step 15
| Go to
Step 16
|
15
| The refrigeration system is operating
properly.
Verify that the control portion of the A/C system is operating properly.
Refer to
Functional Check
.
Did you perform the functional test?
| --
| System OK
| --
|
16
| Observe the compressor operation
during the performance test.
Does the compressor cycle?
| --
| Go to
Step 17
| Go to
Step 18
|
17
|
- Recover the refrigerant. Refer to Refrigerant Recovery and Recharging
.
- Verify that the expansion (orifice) tube is not plugged. Refer
to
Expansion (Orifice) Tube Replacement
.
- Recharge the A/C compressor. Refer to Refrigerant Recovery and Recharging
.
Is the repair complete?
| --
| System OK
| --
|
18
|
- The compressor runs continuously.
- Recover the refrigerant. Refer to Refrigerant Recovery and Recharging
.
- Inspect to see if the expansion (orifice) tube missing.
Is the expansion orifice tube missing?
| --
| Go to
Step 19
| Go to
Step 20
|
19
|
- Install a new expansion tube. Refer to
Expansion (Orifice) Tube Replacement
.
- Recharge the A/C system. Refer to Refrigerant Recovery and Recharging
.
Is the repair complete?
| --
| System OK
| --
|
20
| Examine the suction line between the compressor and the
pressure cycling switch.
Did you find a restriction?
| --
| Go to
Step 21
| Go to
Step 22
|
21
|
- Repair as required.
- Recharge the A/C system. Refer to Refrigerant Recovery and Recharging
.
Is the repair complete?
| --
| System OK
| --
|
22
| A system overcharge is indicated. Recover and recharge
the A/C system. Refer to Refrigerant Recovery and Recharging
.
Is the repair complete?
| --
| System OK
| --
|
Step
| Action
| Value(s)
| Yes
| No
|
1
| Inspect for any stored DTCs.
Are any DTCs stored?
| --
| Go to
Step 2
| Go to
Step 3
|
2
| Correct any stored DTCs. Refer to
DTC Table
.
Are all of the DTCs corrected?
| --
| System OK
| --
|
3
| Connect the J 39500-B
A/C Refrigerant Recovery
Are pressures above the specified value?
| 350 kPa (50 psi)
| Go to
Step 5
| Go to
Step 4
|
4
| The system
is undercharged.
- Add 1 lb of refrigerant.
- Perform the leak check procedure. Refer to
Leak Testing
.
- Repair the leak.
- Recheck the system performance.
Is the cooling insufficient?
| --
| Go to
Step 5
| System OK
|
5
|
- Perform a visual inspection. Inspect for the following conditions:
• | A disconnected A/C clutch wire |
• | Condenser and radiator restrictions |
• | Correct A/C clutch rotation |
- Read the DCS for bulletins or hints.
- Verify that the ambient temperature is not less than the specified
value.
- Idle the engine at normal operating temperature.
- Turn the A/C to the ON position.
- Set the temperature control to the MAX COLD position.
- Set the blower control to the HIGH position.
- Record the A/C pressures and temperatures. Refer to
System Performance Test
.
Are the A/C pressures and temperatures within specified limits?
| 5°C (41°F)
| Go to
Step 6
| Go to
Step 8
|
6
| Did the customer indicate that either high temperature or high humidity
caused the problem?
| --
| Go to
Step 7
| System OK
|
7
| The following conditions may cause high temperature or
high humidity:
- Perform the leak test. Refer to
Leak Testing
.
- Recover and recharge the A/C system. Refer to Refrigerant Recovery and Recharging
.
Did you complete the repair?
| --
| System OK
| --
|
8
| Does the A/C compressor clutch engage?
| --
| Go to
System Performance Test
| Go to
HVAC Compressor Clutch Does Not Engage
|
Gray Area Diagnosis and Service
Problem
| Action
|
DEFINITION:
Inspect the following components if the pressure values intersect in the gray
area of the chart.
|
The condenser operates improperly.
| Improper condenser operation may
result from the following conditions:
• | Extremely high ambient humidity |
• | Insufficient air flow across the condenser |
• | Damaged or dirty condenser fins |
Clean or repair the components as necessary.
|
A high side refrigerant
restriction exists.
|
- Feel the liquid line in front of the expansion (orifice) tube.
If the line feels cold, a restriction in the high side may be present.
- Visually inspect for a frost spot in order to locate the restriction.
Remove any restrictions as necessary.
|
The refrigerant system is overcharged. The following conditions are present:
• | A high discharge pressure exists. |
• | A high suction pressure exists. |
| The clutch
may cycle ON/OFF (see note). This condition may result in a noisy compressor.
- Recover the refrigerant from the A/C system. Refer to Refrigerant Recovery and Recharging
.
- Inspect the expansion (orifice) tube for a blockage. Refer to
Expansion (Orifice) Tube Replacement
.
Clean or replace the tube as necessary.
- Recharge the A/C system. Refer to Refrigerant Recovery and Recharging
.
- Inspect the system for leaks. Refer to
Leak Testing
.
|
• | The expansion (orifice) tube is blocked (low suction pressures
exist). |
• | Air is in the system. The following conditions are present: |
- | A high discharge pressure exists. |
- | A high suction pressure exists. |
|
- Recover the refrigerant from the A/C system. Refer to Refrigerant Recovery and Recharging
.
- Inspect the expansion (orifice) tube for a blockage. Refer to
Expansion (Orifice) Tube Replacement
.
Clean or replace the tube as necessary.
- Recharge the A/C system. Refer to Refrigerant Recovery and Recharging
.
- Inspect the system for leaks. Refer to
Leak Testing
.
|
|
NOTE: V5 clutch cycling may occur
when the discharge pressure exceeds 2758 kPa (400 psi).
|
Striped Area Diagnosis and Service
Problem
| Action
|
DEFINITION: Inspect the following components if pressure values intersect
in the striped area of the chart.
|
The compressor has internal damage.
|
• | If the suction and the discharge pressures are equal and do not
change when you turn the A/C mode ON and OFF, then the compressor may be internally
damaged. |
• | Excess heat at the clutch surfaces or a free wheeling clutch driver
are signs of internal compressor damage. |
• | When replacing the compressor, follow the component replacement
procedures in order to maintain the correct oil charge in the system. |
|
The expansion (orifice) tube is missing.
|
- Feel the liquid line behind the expansion (orifice) tube.
• | If the line is warm, recover the refrigerant. Refer to Refrigerant Recovery and Recharging
. Inspect the
system for proper installation of the expansion tube. Refer to
Expansion (Orifice) Tube Replacement
. Reinstall
the tube if necessary. |
• | If the expansion tube or the O-ring is missing, replace the expansion
tube. |
- Recharge the A/C system. Refer to Refrigerant Recovery and Recharging
.
|
The compressor is at minimum stroke.
| High Load TestIf the compressor discharge pressures remain only 69-207 kPa
(10-30 psi) above the suction pressure, then the compressor may be
at minimum stroke. Perform the following procedure:
- Run the engine at approximately 3000 RPM for 3 minutes
until the pressures return to normal.
- During this period, cycle the mode lever from the VENT position
to the A/C position every 20 seconds.
- Observe the pressure. If no change occurs, perform the Low Load
Test.
|
The compressor control valve is set improperly.
| Low Load TestThe low load test procedure creates a low cooling load. This condition
causes the V5 compressor to operate toward minimum stroke. Use the
following test procedure for evaluation of the control valve set point:
- Start the engine.
- Run the engine at a fast idle.
- Open the hood. Close all of the windows and the doors.
- Select the A/C mode.
- Set the blower control to the LOW position.
- Set the temperature control to the MAX COLD position.
- Record and evaluate the test results:
• | If the suction pressure is within 172-241 kPa (25-35 psi),
the control valve is functioning properly. |
• | If the suction pressure outside the range of 172-241 kPa
(25-35 psi), replace the control valve. |
|
The refrigerant system is undercharged.
| The refrigerant system may be undercharged when the suction
pressure is below 241 kPa (35 psi) during the High Load Test.
If the charge is low, the suction line before the accumulator will be
warm.
- Add 1 lb of refrigerant.
- Inspect the suction pressure again.
Ensure that the pressure values are within the white (normal) area on
the chart. If the pressure valves are normal, find the source of the refrigerant
leak. Repair the leak as necessary.
- Recharge the A/C system. Refer to Refrigerant Recovery and Recharging
.
|
The expansion (orifice) tube is blocked.
|
- Recover the refrigerant from the A/C system. Refer to Refrigerant Recovery and Recharging
.
- Inspect the expansion (orifice) tube for a blockage. Refer to
Expansion (Orifice) Tube Replacement
.
- Clean or replace the tube as necessary.
- Recharge the A/C system. Refer to Refrigerant Recovery and Recharging
.
- Inspect the system for leaks. Refer to
Leak Testing
.
|