LEMON Manuals: Even more car manuals for everyone
Home >> Isuzu >> 2007 >> i-290 LS, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 10 (Heating, Ventilation, And Air Conditioning) >> Diagnostic Information and Procedures >> Air Conditioning (A/C) Diagnostics - Pressure Zone B

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

WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
Air Conditioning (A/C) Diagnostics - Pressure Zone B

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 high side pressures equalize or become static? Go to Step 5  Go to Step 3 
3
  1. Refer to the pressures recorded during the A/C System Performance Test.
  2. Inspect for the following conditions:
      CAUTION: Refer to Moving Parts and Hot Surfaces Caution .
    • 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 below the specified pressure range of the A/C Performance Table. Refer to Air Conditioning (A/C) System Performance Test  .
    • The low side refrigerant line at the compressor feels cool-to-warm.
    • The high side refrigerant line at the compressor feels warm-to-hot.
Do the listed conditions exist?		 Go to Step 5  Go to Step 4 
4
  1. Refer to the pressures recorded during the A/C System Performance Test.
  2. Inspect for the following conditions:
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 action complete?		 Go to Step 6  -
6
  1. After you perform the repairs, record the following information:
    • The low and the high side pressures
    • The instrument panel outlet air temperature
  2. 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
  1. The A/C compressor is malfunctioning.
  2. 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
  1. Remove the discharge hose from the compressor. Refer to Discharge Hose Replacement .
  2. Remove the suction hose from the compressor. Refer to Suction Hose Replacement .
  3. Inspect for metal flake contamination at the line connections and the compressor ports.
Is metal flake contamination present?		 Go to Step 10  Go to Step 12 
10
  1. Replace the A/C compressor. Refer to Compressor Replacement .
  2. Replace the thermal expansion valve (TXV). Refer to Thermal Expansion Valve Replacement .
  3. Evacuate and recharge the A/C system. Refer to Refrigerant Recovery and Recharging .
Is the action complete?		 Go to Step 13  -
11
  1. Flush the A/C system. Refer to Flushing .
  2. Replace the TXV. Refer to Thermal Expansion Valve Replacement .
  3. Replace the A/C compressor. Refer to Compressor Replacement .
  4. Replace the condenser. Refer to Condenser Replacement .
  5. Evacuate and recharge the A/C system. Refer to Refrigerant Recovery and Recharging .
Is the action complete?		 Go to Step 13  -
12
  1. Replace the A/C compressor. Refer to Compressor Replacement .
  2. Evacuate and recharge the A/C system. Refer to Refrigerant Recovery and Recharging .
Is the action 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 - Automatic
scientia non olet · About LEMON Manuals