Step
| Action
| Yes
| No
|
DEFINITION: The low side pressure is lower than normal and the
high side pressure is higher than normal.
A restriction in the A/C system.
|
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
|
Caution: Refer to Moving Parts and Hot Surfaces Caution in the Preface section. Feel the liquid line before the expansion device.
Is the liquid line cold before the expansion device?
| Go to
Step 3
| Go to
Step 8
|
3
| Feel along the surfaces of the following high side components for a sudden
drop in temperature. The high side components should feel warm/hot from the
compressor all the way to the expansion device.
• | The compressor discharge hose |
• | The liquid line between the condenser and the expansion device |
Is there an abrupt drop in temperature noted along the surfaces of any of
the listed components?
| Go to
Step 7
| Go to
Step 4
|
4
|
- Feel the liquid line at the expansion device location for extreme
cold, possibly accompanied by heavy frost.
- Feel along the liquid line after the expansion device location
for warm temperature.
Is the liquid line extremely cold at the expansion device location and warm
after the expansion device location?
| Go to
Step 11
| Go to
Step 5
|
5
| Feel along the surfaces of the following low side components for a sudden
change in temperature.
• | The evaporator inlet tube between the expansion device and the evaporator
core |
• | The evaporator outlet tube between the evaporator core and the compressor. |
• | The compressor suction hose |
Is there an abrupt temperature change felt along the surfaces of any of the
listed components?
| Go to
Step 7
| Go to
Step 6
|
6
| Feel along the surfaces of low and high side components to compare the overall
temperatures.
• | The evaporator inlet tube between the expansion device and the evaporator
core |
• | The evaporator outlet tube between the evaporator core and the accumulator |
• | The compressor suction hose |
• | The compressor discharge hose |
• | The evaporator inlet tube between the condenser and the expansion
device |
Are the overall temperatures of the low and high side components close to
the same, both only mildly warm?
| Go to
Step 14
| Go to
Step 8
|
7
|
- Recover the refrigerant. Refer to
Refrigerant Recovery and Recharging
.
- Remove the restriction from the component, or replace the component
which produced an abrupt temperature drop.
Is the repair complete?
| Go to
Step 9
| --
|
8
|
- Recover the refrigerant and evacuate the system. Refer to
Refrigerant Recovery and Recharging
.
- Record the weight of the recovered refrigerant.
Is the weight of the recovered refrigerant charge equal to or above the specified
value?
| Go to
Step 10
| Go to
Step 10
|
9
| Recharge the A/C system. Refer to
Refrigerant Recovery and Recharging
.
Is the cooling performance improved?
| Go to
Step 21
| Go to
Step 10
|
10
|
- Leak test the system. Refer to
Leak Testing
.
- Repair any leaks.
Is the repair complete?
| Go to
Step 21
| --
|
11
|
- The expansion device is restricted.
- Replace the expansion device. Refer to
Expansion (Orifice) Tube Replacement
.
- If the expansion device was restricted, note the type of debris
present.
Are there metal flakes present?
| Go to
Step 12
| Go to
Step 13
|
12
|
- Remove the compressor hose assembly from the vehicle. Refer to
Compressor Hose Assembly Replacement
.
- Inspect the hose/line for debris by blowing shop air through one
end of the hose while covering the other end with a shop towel.
- Note the amount of debris collected in the shop towel.
Is there a large amount of debris collected in the shop towel?
| Go to
Step 18
| Go to
Step 20
|
13
| If the expansion device was restricted with a brown/black residue, perform
the following:
- Flush the A/C system. Refer to
Flushing
- Replace the accumulator. Refer to
Air Conditioning Accumulator Replacement
.
Are the repairs complete?
| Go to
Step 21
| --
|
14
|
- Recover the refrigerant. Refer to
Refrigerant Recovery and Recharging
.
- Disconnect the compressor hose from the compressor. Refer to
Compressor Hose Assembly Replacement
.
- Inspect for the presence of debris in the compressor suction port.
Is there debris present in the compressor suction port?
| Go to
Step 15
| Go to
Step 19
|
15
|
- Remove the debris from the suction port.
- Inspect the expansion device for damage or debris. Refer to
Expansion (Orifice) Tube Replacement
.
Is there evidence of damage or debris?
| Go to
Step 17
| Go to
Step 16
|
16
| If the expansion device does not show any signs of damage or debris:
- Remove the compressor hose assembly from the vehicle. Refer to
Compressor Hose Assembly Replacement
.
- Inspect the hose/line for debris by blowing shop air through one
end of the hose while covering the other end with a shop towel.
- Note the amount of debris collected in the shop towel.
Is there a large amount of debris collected in the shop towel?
| Go to
Step 18
| Go to
Step 19
|
17
|
- Replace the expansion device. Refer to
Expansion (Orifice) Tube Replacement
.
- If the expansion device was restricted, note the type of debris
present.
Are there metal flakes present?
| Go to
Step 12
| Go to
Step 13
|
18
| If there was a large amount of debris collected in the shop towel from the
compressor hose assembly:
- Replace the accumulator. Refer to
Air Conditioning Accumulator Replacement
.
- Install an A/C refrigerant filter. Refer to
Air Conditioning Evaporator Thermal Expansion Valve Screen Replacement
.
- Install a suction screen. Refer to
Suction Screen Installation
Is the repair complete?
| Go to
Step 19
| --
|
19
| Install the compressor hose assembly. Refer to
Compressor Hose Assembly Replacement
.
Are the repairs complete?
| Go to
Step 21
| --
|
20
|
- Install the compressor hose assembly. Refer to
Compressor Hose Assembly Replacement
.
- Install an A/C refrigerant filter. Refer to
Air Conditioning Evaporator Thermal Expansion Valve Screen Replacement
.
- Recharge the A/C system. Refer to
Refrigerant Recovery and Recharging
.
Are the repairs complete?
| Go to
Step 21
| --
|
21
|
- Record the low and high side pressures and the IP outlet air temperature
after repairs are performed.
- Compare the pressures and outlet temperature to those listed in
the A/C Performance Chart. Refer to
Air Conditioning (A/C) System Performance Test
.
Are the readings within the specified ranges?
| Go to
Step 22
| Go to
Air Conditioning (A/C) System Performance Test
|
22
| Operate the system in order to verify the repair.
Did you find and correct the condition?
| System OK
| Go to
Symptoms - HVAC Systems - Manual
|