LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2006 >> Silverado 1500 HD, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1298 (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 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. 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 (Diesel Engine) , Air Conditioning (A/C) System Performance Test (Gas Engine w/Electric Cooling Fan) , Air Conditioning (A/C) System Performance Test (Gas Engine w/Engine Driven Fan)  or Air Conditioning (A/C) System Performance Test (HP2 ) 
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:
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:
Do the listed conditions exist ?		 Go to Step 5  Go to Air Conditioning (A/C) System Performance Test (Diesel Engine) , Air Conditioning (A/C) System Performance Test (Gas Engine w/Electric Cooling Fan) , Air Conditioning (A/C) System Performance Test (Gas Engine w/Engine Driven Fan)  or Air Conditioning (A/C) System Performance Test (HP2 ) 
5 The A/C system has a low refrigerant charge.
Evacuate and recharge the A/C system. Refer to Refrigerant Recovery and Recharging (Non-HP2)  or Refrigerant Recovery and Recharging (HP2) .
Is the procedure complete?		 Go to Step 6  -
6
  1. Record the low and the high side pressures as well as the instrument panel (I/P) air outlet temperature after you perform the repairs.
  2. Compare the pressures and the panel outlet temperature to those listed in the A/C Performance Chart. Refer to Air Conditioning (A/C) System Performance Test (Diesel Engine) , Air Conditioning (A/C) System Performance Test (Gas Engine w/Electric Cooling Fan) , Air Conditioning (A/C) System Performance Test (Gas Engine w/Engine Driven Fan)  or Air Conditioning (A/C) System Performance Test (HP2 ) .
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 Expansion (Orifice) Tube 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 suction and the discharge lines from the compressor. Refer to Suction Hose Replacement (LY2, LMF, L76 and L92) , Suction Hose Replacement (LMM)  and Discharge Hose Replacement (LMM)  or Discharge Hose Replacement (LY2, LMF, L76 and L92) .
  2. 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 Air Conditioning Compressor Replacement (LLY/LMM) , Air Conditioning Compressor Replacement (LU3) , Air Conditioning Compressor Replacement (LY2, LY5, LH6, L76, L92 and LMG)  or Air Conditioning Compressor Replacement (HP2) .
  2. Replace the orifice tube. Refer to Expansion (Orifice) Tube Replacement .
  3. Evacuate and recharge the A/C system. Refer to Refrigerant Recovery and Recharging (Non-HP2)  or Refrigerant Recovery and Recharging (HP2) .
Is the repair complete?		 Go to Step 13  -
11
  1. Flush the A/C system. Refer to Flushing (Non HP2)  or Flushing (HP2) .
  2. Replace the orifice tube. Refer to Expansion (Orifice) Tube Replacement .
  3. Replace the A/C compressor. Refer to Air Conditioning Compressor Replacement (LLY/LMM) , Air Conditioning Compressor Replacement (LU3) , Air Conditioning Compressor Replacement (LY2, LY5, LH6, L76, L92 and LMG)  or Air Conditioning Compressor Replacement (HP2) .
  4. Replace the accumulator. Refer to Air Conditioning Accumulator Replacement (Non-HP2) .
  5. Evacuate and recharge the A/C system. Refer to Refrigerant Recovery and Recharging (Non-HP2)  or Refrigerant Recovery and Recharging (HP2) .
Is the repair complete?		 Go to Step 13  -
12
  1. Replace the A/C compressor. Refer to Air Conditioning Compressor Replacement (LLY/LMM) , Air Conditioning Compressor Replacement (LU3) , Air Conditioning Compressor Replacement (LY2, LY5, LH6, L76, L92 and LMG)  or Air Conditioning Compressor Replacement (HP2) .
  2. Evacuate and recharge the A/C system. Refer to Refrigerant Recovery and Recharging (Non-HP2)  or Refrigerant Recovery and Recharging (HP2) .
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 - Automatic
scientia non olet · About LEMON Manuals