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

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

Step Action Yes No
DEFINITION: The low and the high side pressures are both higher than normal.
  • Restricted Condenser Air Flow
  • Cooling Fan Malfunction
  • Expansion Device Malfunction
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 (Short Wheel Base)  or Air Conditioning (A/C) System Performance Test (Long Wheel Base - 1500 Series)  or Air Conditioning (A/C) System Performance Test (Long Wheel Base - 2500 Series) 
2
  1. With the engine idling, turn ON the A/C.
  2. Inspect for proper cooling fan operation. Refer to Cooling System Description and Operation .
Are the cooling fans ON and operating properly?		 Go to Step 3  Go to Step 5 
3 Visually inspect for the following:
  • Restricted air flow.
  • Damaged condenser cooling fins.
  • Inspect for missing or misaligned air baffles.

Do the following conditions exist?		 Go to Step 4  Go to Step 6 
4 Repair the air flow restriction.
Is the repair complete?		 Go to Step 9  -
5 Repair the cooling fan operation fault. Refer to Symptoms - Engine Cooling in Engine Cooling.
Is the repair complete?		 Go to Step 9  -
6
CAUTION: Refer to Moving Parts and Hot Surfaces Caution .
Feel the liquid line on both sides of the expansion device.Is the temperature the same before and after the expansion device?		 Go to Step 7  Go to Step 8 
7 Replace the damaged/faulty orifice tube. Refer to Expansion (Orifice) Tube Replacement (W/O C69)  or Expansion (Orifice) Tube Replacement (W/C69) .
Is the repair complete?		 Go to Step 9  -
8 Air is in the refrigerant system, or the system is overcharged. Refer to the view screen on the J 43600  ACR 2000 Air Conditioning Service Center for foreign gas content in the refrigerant. See Special Tools .
Recover and recharge the A/C system. Refer to Refrigerant Recovery and Recharging .
Is the repair complete?		 Go to Step 9  -
9
  1. Record the low and high side pressures and the I/P outlet air temperature after repairs are performed.
  2. Compare the pressures and outlet temperature to those listed in the A/C Performance Chart. Refer to Air Conditioning (A/C) System Performance Test (Short Wheel Base)  or Air Conditioning (A/C) System Performance Test (Long Wheel Base - 1500 Series)  or Air Conditioning (A/C) System Performance Test (Long Wheel Base - 2500 Series) .
Are the readings within the specified ranges?		 Go to Step 10  Go to Air Conditioning (A/C) System Performance Test (Short Wheel Base)  or Air Conditioning (A/C) System Performance Test (Long Wheel Base - 1500 Series)  or Air Conditioning (A/C) System Performance Test (Long Wheel Base - 2500 Series) 
10 Operate the system in order to verify the repair.
Did you find and correct the condition?		 System OK Go to Symptoms - HVAC Systems - Manual
or
Symptoms - HVAC Systems - Automatic
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