DEFINITION: The high and low side pressures may be normal or slightly less than normal.

Were you sent here from the A/C System Performance Test?

Go to Step 2

Go to Air Conditioning (A/C) System Performance Test

Refer to the panel air outlet temperatures recorded during the A/C system performance test.

Does the discharge air temperature between the right and left center panel outlets vary by more than 1-2°C (2-3°F)?

Go to Step 7

Go to Step 3

Did the customer mention that the A/C system output temperatures are good at first, but then turn warm during extended drives?

Go to Step 4

Go to Step 5

Increase engine speed to 2000 RPM.

During extended operation of the A/C system, does the low side pressure decrease, possibly accompanied by heavy frost on the liquid line between the expansion device and the evaporator?

Go to Air Conditioning (A/C) Diagnostics - Pressure Zone D

Go to Step 5

Refer to the pressures recorded during the A/C system performance test.

Inspect for the following conditions:

Caution: Refer to Moving Parts and Hot Surfaces Caution in the Preface section.

Do the listed conditions exist?

Go to Step 7

Go to Step 6

Refer to the pressures recorded during the A/C system performance test.

Inspect for the following conditions:

Caution: Refer to Moving Parts and Hot Surfaces Caution in the Preface section.

Do the listed conditions exist?

Go to Step 8

Go to Air Temperature Malfunction

The A/C system may be undercharged.

1. Leak test A/C system. Refer to Leak Testing .
2. Recharge the A/C system to specifications. Refer to Refrigerant Recovery and Recharging .

Is the repair complete?

Go to Step 14

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The A/C system may be contaminated.

Do foreign gases exist?

Go to Step 9

Go to Step 10

1. Evacuate the A/C system to a scavenging tank. Refer to Refrigerant Recovery and Recharging .
2. Recharge the A/C system to specifications.

Is the repair complete?

Go to Step 14

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The A/C system may contain too much moisture or air.

1. Evacuate and recharge the A/C system to specifications. Refer to Refrigerant Recovery and Recharging .
2. Operate the A/C system and inspect the panel outlet air temperatures. Refer to Air Conditioning (A/C) System Performance Test .

Are the panel outlet temperatures within the specified ranges of the A/C Performance Test Table?

Go to Step 15

Go to Step 11

The A/C system may contain too much refrigerant oil.

1. Recover the refrigerant from the A/C system. Refer to Refrigerant Recovery and Recharging .
2. Remove the accumulator. Refer to Air Conditioning Accumulator Replacement .
3. Drain and measure the refrigerant oil from the accumulator.

Were more than 148 ml (5 oz) of refrigerant oil drained from the accumulator?

Go to Step 12

Go to Step 13

1. Reinstall the accumulator. Refer to Air Conditioning Accumulator Replacement .
2. Add the specified amount of refrigerant oil to the accumulator. Refer to Refrigerant System Capacities .
3. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging .

Are the repairs complete?

Go to Step 14

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1. Add the specified amount of refrigerant oil to the accumulator. Refer to Refrigerant System Capacities .
2. Install the accumulator. Refer to Air Conditioning Accumulator Replacement .
3. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging .

Are the repairs complete?

Go to Step 14

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1. Record the low and high side pressures and the IP outlet air temperature.
2. Compare the outlet temperatures to those listed in the A/C System Performance Chart. Refer to Air Conditioning (A/C) System Performance Test .

Are the high and low side pressures and IP panel outlet temperatures within specifications?

Go to Step 15

Go to Air Conditioning (A/C) System Performance Test

Operate the system in order to verify the repair.

Did you find and correct the condition?

System OK

Go to Symptoms - HVAC Systems - Manual