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

WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
Step Action Value 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.
  • Debris in the 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 .
Feel the liquid line at the front of dash.Is the liquid line cold at the front of dash?		 - Go to Step 3  Go to Step 8 
3 Feel along the surface of the liquid line between the condenser and the front of dash.
Did you detect an abrupt drop in temperature along the surface?		 - Go to Step 5  Go to Step 4 
4 Feel along the surfaces of the following low side components:
  • The evaporator outlet tube between the front of dash and the compressor suction hose
  • The compressor suction hose to the compressor.

Did you feel an abrupt temperature change along the surfaces of any of the listed components?		 - Go to Step 5  Go to Step 6 
5
  1. Recover the refrigerant. Refer to Refrigerant Recovery and Recharging .
  2. Remove the restriction from the component, or replace the component which produced an abrupt temperature drop.
  3. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging .
Is the repair complete?		 - Go to Step 13  -
6 The system may be low charged.
  1. Recover the refrigerant. Refer to Refrigerant Recovery and Recharging .
  2. Record the weight of the recovered refrigerant.

Is the weight of the recovered refrigerant charge less than the specified value?		 Standard AC 0.625 kg (1.38 lbs) Go to Step 7  Go to Step 10 
7 The expansion device may be restricted or failed.
  1. Remove the expansion device. Refer to Thermal Expansion Valve Replacement .
  2. Check the expansion device for a large amount residue at the inlet.

Did you notice a residue at the inlet to the expansion device?		 - Go to Step 8  Go to Step 11 
8 The desiccant bag in the receiver portion of the condenser may have failed.
  1. Remove the desiccant bag from the condenser. Refer to Air Conditioning Refrigerant Desiccant Replacement .
  2. Check to see if the bag was broken.

Was the bag broken or leaking?		 - Go to Step 9  Go to Step 12 
9
  1. Flush the A/C system. Refer to Flushing .
  2. Replace the condenser. Refer to Condenser Replacement .
  3. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging .
Are the repairs complete?		 - Go to Step 13  -
10
  1. Leak test the system. Refer to Leak Testing .
  2. Repair any leaks found.
  3. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging .
Are the repairs complete?		 - Go to Step 13  -
11
  1. Replace the expansion device.
  2. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging .
Are the repairs complete?		 - Go to Step 13  -
12
  1. Replace the desiccant bag with a new unit.
  2. Replace the expansion device.
  3. Recharge the A/C system. Refer to Refrigerant Recovery and Recharging .
Are the repairs complete?		 - Go to Step 13  -
13
  1. Record the low and the high side pressures and the panel outlet air temperature.
  2. Compare the pressures and the panel outlet temperature to those listed in the A/C Performance Table. Refer to Air Conditioning (A/C) System Performance Test .
Are the readings within the specified ranges as shown on the A/C performance Table?		 - Go to Step 14  Go to Air Conditioning (A/C) System Performance Test 
14 Operate the system in order to verify the repair.
Did you find and correct the condition?		 - System OK Go to Symptoms - HVAC Systems - Automatic
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