Step
| Action
| Value
| Yes
| No
|
DEFINITION:
The low side pressure is higher than normal and the high side pressure is lower than normal.
| • | Malfunctioning A/C Compressor |
| • | Refrigerant Under Charge |
|
1
| Were you sent here from the A/C System Performance Test?
| --
| Go to
Step 2
| Go to
Air Conditioning (A/C) System Performance Test
|
2
| Refer to the pressures recorded during the A/C System Performance Test.
Inspect for the following conditions:
Warning: Refer to Moving Parts and Hot Surfaces Warning in the Preface section.
| • | The low side refrigerant line at the compressor feels cool to cold. |
| • | The high side refrigerant line at the compressor feels warm-to-hot. |
Do the listed conditions exist?
| --
| Go to
Step 3
| Go to
Step 7
|
3
| The A/C system may be undercharged or have compressor or expansion valve problems.
- Leak test the A/C system. Refer to
Leak Testing.
- Note any potential leaks for later repair.
- Recover the refrigerant charge from the vehicle. Refer to
Refrigerant Recovery and Recharging.
- Record the weight of the recovered refrigerant.
Is the recovered amount below the specified values?
| Standard A/C 0.625 kg (1.38 lbs)
| Go to
Step 4
| Go to
Step 6
|
4
| The system is low on refrigerant charge.
- Repair any leaks noted in step 3 above.
- Evacuate and Recharge the A/C system to specifications. Refer to
Refrigerant Recovery and Recharging.
Is the repair complete?
| --
| Go to
Step 5
| --
|
5
|
- Record the low and high side pressures and the instrument panel (I/P) outlet temperatures. Refer to step 2 of the Air Conditioning (A/C) System Performance Test.
- Compare the panel outlet temperatures and pressures to those listed in the A/C System Performance Chart.
Are the high and low side pressures and I/P outlet temperatures within specification?
| --
| System OK
| Go to
Air Conditioning (A/C) System Performance Test
|
6
| The thermal expansion valve needs to be replaced.
- Replace the thermal expansion valve. Refer to
Air Conditioning Evaporator Thermal Expansion Valve Replacement.
- Repair any leaks noted in step 3 above.
- Evacuate and recharge the A/C system to specifications. Refer to
Refrigerant Recovery and Recharging.
Is the repair complete?
| --
| Go to
Step 5
| --
|
7
| Refer to the pressures recorded during the A/C System Performance Test.
Inspect for the following conditions:
Warning: Refer to Moving Parts and Hot Surfaces Warning in the Preface section.
| • | The low side refrigerant line at the compressor feels warm. |
| • | The high side refrigerant line at the compressor feels warm to hot. |
Do the listed conditions exist?
| --
| Go to
Step 8
| Go to
Air Conditioning (A/C) System Performance Test
|
8
| The system could be low charged or there could be a problem with the A/C compressor.
- Verify that the compressor is engaging properly.
- Verify that the A/C system performance data was taken with the compressor clutch engaged for more than 10 seconds.
- Increase engine speed to 1,200 RPM.
- Record the low and high side pressures and the I/P outlet air temperatures. Refer to step 2 of the Air Conditioning (A/C) System Performance Test.
- Compare the panel outlet temperatures and pressures to those listed in the A/C System Performance Chart.
Are the high and low side pressures and I/P outlet temperatures within specification?
| --
| Go to
Step 3
| Go to
Step 9
|
9
| With the engine speed raised to over 2,000 RPM and the A/C compressor clutch engaged, listen for any unusual compressor noise.
Any unusual noises heard?
| --
| Go to
Step 3
| Go to
Step 10
|
10
|
- Replace the A/C compressor. Refer to
Air Conditioning Compressor Replacement.
- Evacuate and recharge the A/C system. Refer to
Refrigerant Recovery and Recharging.
Is the repair complete?
| --
| Go to
Step 11
| --
|
11
| Operate the system in order to verify the repair.
Did you find and correct the condition?
| --
| System OK
| Go to
Symptoms - HVAC Systems - Automatic
|
