Air Conditioning (A/C) Diagnostics - Pressure Zone B

WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

Step	Action	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	After continued operation of the A/C system, do the low and the high side pressures equalize or become static?	Go to Step 5	Go to Step 3
3	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 Cautions and Notices. The low side pressure is equal to or greater than the specified pressure range of the A/C Performance Table. Refer to Air Conditioning (A/C) System Performance Test . The high side pressure is less than the specified pressure range of the A/C Performance Table. Refer to Air Conditioning (A/C) System Performance Test . The low side refrigerant hose at the compressor feels cool-to-warm. The high side refrigerant hose at the compressor feels warm-to-hot. Do the listed conditions exist?	Go to Step 5	Go to Step 4
4	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 Cautions and Notices. The low side pressure is greater than the specified pressure range of the A/C Performance Table. Refer to Air Conditioning (A/C) System Performance Test . The high side pressure is less than the specified pressure range of the A/C Performance Table. Refer to Air Conditioning (A/C) System Performance Test . The low side refrigerant hose at the compressor feels warm. The high side refrigerant hose at the compressor feels warm to hot. Do the listed conditions exist?	Go to Step 5	Go to Air Conditioning (A/C) System Performance Test
5	The A/C system has a low refrigerant charge. Evacuate and recharge the A/C system. Refer to Refrigerant Recovery and Recharging . Is the procedure complete?	Go to Step 6	-
6	After you perform the repairs, record the following: The low and the high side pressures The instrument panel (I/P) outlet air temperature Compare the pressures and the 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 found on the A/C Performance Chart?	Go to Step 13	Go to Step 7
7	The A/C compressor is malfunctioning. Remove the expansion device and inspect for contamination. Refer to Thermal Expansion Valve Replacement . Did you find metal flakes on the expansion device?	Go to Step 9	Go to Step 8
8	Inspect the expansion device for a brown, powdery residue indicating desiccant in the A/C system. Is a brown, powdery residue present?	Go to Step 11	Go to Step 12
9	Remove the suction and the discharge hoses from the compressor. Refer to Suction Hose Replacement (LA1) or Suction Hose Replacement (LY7) and Discharge Hose Replacement (LA1) or Discharge Hose Replacement (LY7) . Inspect for metal flake contamination at the hose connections and the compressor ports. Is metal flake contamination present?	Go to Step 10	Go to Step 12
10	Replace the A/C compressor. Refer to Compressor Replacement . Replace the receiver dehydrator. Refer to Receiver Dehydrator Replacement . Replace the thermal expansion valve. Refer to Thermal Expansion Valve Replacement . Evacuate and recharge the A/C system. Refer to Refrigerant Recovery and Recharging . Is the repair complete?	Go to Step 13	-
11	Flush the A/C system. Refer to Flushing . Replace the thermal expansion valve. Refer to Thermal Expansion Valve Replacement . Replace the A/C compressor. Refer to Compressor Replacement . Replace the receiver dehydrator. Refer to Receiver Dehydrator Replacement . Evacuate and recharge the A/C system. Refer to Refrigerant Recovery and Recharging . Is the repair complete?	Go to Step 13	-
12	Replace the A/C compressor. Refer to Compressor Replacement . Evacuate and recharge the A/C system. Refer to Refrigerant Recovery and Recharging . Is the repair complete?	Go to Step 13	-
13	Operate the system in order to verify the repair Did you find and correct the condition?	System OK	Go to Symptoms - HVAC Systems - Manual in HVAC Systems - Manual or Symptoms - HVAC Systems - Automatic in HVAC Systems - Automatic