Cooling Insufficient - Air Conditioning (A/C) System - Pressure Zone A. Pontiac Montana 2000

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 2000 🢒 Montana 🢒 HVAC 🢒 Heating, Ventilation and Air Conditioning 🢒 Cooling Insufficient - Air Conditioning (A/C) System - Pressure Zone A

A/C System Pressure -- Zone Classification

Step

Action

Value(s)

Yes

Were you sent here from the Cooling Insufficient, A/C System diagnostic table?

Go to Step 2

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

Refer to the air outlet temperatures recorded

Is there a difference in air discharge temperature between the right and left center I/P outlets?

Go to Step 9

Go to Step 3

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

Go to Step 4

Go to Step 5

The engine still running with a speed of 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 orifice and the evaporator)?

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

Go to Step 5

Refer to the low and high side pressures recorded.

Inspect for the following conditions:

•	The high side pressure slightly above the specified pressure ranges but still within zone A on the A/C Pressure-Zone Classification Chart above

•	The discharge line is hot

•	The suction line is cool

Do the listed conditions exsist?

Go to Step 7

Go to Step 6

Refer to the low and high side pressures recorded.

Inspect for the following conditions:

•	The low side pressure slightly lower than the specified ranges but still within the zone A on the A/C Pressure-Zone Classification Chart above

•	The discharge line is warm to hot

•	The suction line is cool to warm

Do the listed conditions exsist?

Go to Step 8

Go to Air Delivery Improper Diagnosis

The A/C system has contamination in it.
Evacuate the A/C system. Refer to Refrigerant Recovery and Recharging .
Check the amount of refrigerant oil removed from the system.
Recharge the A/C system to specifications. Refer to Refrigerant Recovery and Recharging .
Leak test the A/C system. Refer to Leak Testing

Are the repairs completed?

Go to Step 10

The A/C system may contain too much moisture.
Evacuate the A/C system. Refer to Refrigerant Recovery and Recharging .

Important: Pay attention to the sight glass on the ACR4 looking for indication of moisture contamination.

If mositure is indicated by the ACR4, replace the accumulator. Refer to Air Conditioning Accumulator Replacement
Charge the A/C system to specifications. Refer to Refrigerant Recovery and Recharging .
Leak test the A/C system. Refer to Leak Testing

Are the repairs completed?

Go to Step 10

The A/C system is under charged but not enough to show a difference in low or high side pressures.

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

Is the repair complete?

Go to Step 10

Take readings of the low and high side pressures as well as the dash outlet air temperature.

Compare the outlet temperature to those listed in the A/C System Performance Chart. Refer to Cooling Insufficient - Air Conditioning (A/C) System

Are the high and low side pressures and outlet temperature within specifications?

Go to Step 11

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

Operate the sysem in order to verify the repair.

Did you correct the condition ?

System OK

Go to Symptoms in HVAC Systems - Manual