For 1990-2009 cars

#### A/C System Pressure -- Zone Classification

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Were you sent here from the HVAC System Check? | -- | Go to Step 2 | Go to HVAC System Check
2 |

1. If the engine is at operating temperature, allow the engine to cool to room temperature.
2. Ensure that the ignition key is in the OFF position.
3. Connect an R-134a manifold gage set to the low side and high side service ports on the vehicle refrigerant system.
4. Check the low and high side pressures.

The low and high side pressure readings should be almost equal to each other once the system has come to rest.

Are both the low and high side pressures above the specified value?

345 kPa (50 psi)

Go to Step 6

Go to Step 3

3 | Are both the low and high side pressures below the specified value? | 69 kPa (10 psi) | Go to Step 4 | Go to Step 5
4 |

1. Add 0.45 Kg (1 lb) of R-134a.
2. Leak test the refrigerant system. Refer to Leak Testing .
3. Repair the refrigerant leak.
4. Recheck the low and high side refrigerant pressures.

Are both the low and high side refrigerant pressures above the specified value?

345 kPa (50 psi)

Go to Step 6

--

5 |

1. Leak test the refrigerant system. Refer to Leak Testing .
2. Repair the refrigerant leak.
3. Recheck the low and high side refrigerant pressures.

Are both the low and high side refrigerant pressures above the specified value?

345 kPa (50 psi)

Go to Step 6

--

6 |

1. Start the engine and allow the engine to idle.
2. Turn the A/C ON by depressing the A/C button on the HVAC control head.

Does the compressor clutch engage?

--

Go to Step 7

Go to HVAC Compressor Clutch Does Not Engage

7 |

1. Accurately measure and record the both the ambient air humidity level and temperature.

(These figures will be used later.)

2. The engine still idling in PARK.
3. Install a precision thermometer into the I/P center air outlet.
4. Set the HVAC control head to the following positions:

• | A/C button to ON

• | Temperature control to full cold

• | Mode control knob to UPPER (I/P outlets)

• | Blower switch to 5 (high)

5. Elevate and maintain the engine speed at 2000 RPM.
6. Allow the low and high side pressure readings to stabilize, if necessary.

(Stabilization usually requires 2-3 minutes.)

7. Record the low and high pressure readings.
8. Compare the low and high side pressures to the A/C System Pressure -- Zone Classification Chart above.

Refer to

#### A/C System Pressure -- Zone Classification

.

Do both the low and high side pressures fall within Zone A on the chart?

--

Go to Cooling Insufficient - Air Conditioning (A/C) System - Pressure Zone A

Go to Step 8

8

Compare the low and high side pressures to the A/C System Pressure -- Zone Classification Chart above. Refer to

#### A/C System Pressure -- Zone Classification

.

Do both the low and high side pressures fall within Zone B on the chart?

--

Go to Cooling Insufficient - Air Conditioning (A/C) System - Pressure Zone B

Go to Step 9

9

Compare the low and high side pressures to the A/C System Pressure -- Zone Classification Chart above. Refer to

#### A/C System Pressure -- Zone Classification

.

Do both the low and high side pressures fall within Zone C on the chart?

--

Go to Cooling Insufficient - Air Conditioning (A/C) System - Pressure Zone C

Go to Cooling Insufficient - Air Conditioning (A/C) System - Pressure Zone D