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Diagnostic Table

WARNING: This page is about a different car, the 2006 Mercury Mariner and 2006 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
    NOTE: The following table is used to guide diagnosis of the refrigerant system if the operating pressures are outside the normal limits.
  1. Proceed to the DIAGNOSTIC TABLE .
DIAGNOSTIC

High (Discharge) Pressure Low (Suction) Pressure Component - Causes
High or clutch cycling High Condenser - inadequate airflow
High Normal to high Engine - overheating
Normal to high Normal Refrigerant overcharge - air in refrigerant
Normal to low High Fixed orifice tube - missing O-rings leaking/missing
Normal to low Normal to high A/C suction line - partially restricted or plugged(1)
Normal to low Low or clutch cycling Low refrigerant charge, A/C suction line - partially restricted or plugged(2) A/C cycling switch - sticking closed
Erratic operation or compressor not running A/C cycling switch - poor connection at the A/C clutch connector or clutch cycling switch connector. A/C electrical circuit erratic - see the wiring diagram inAIR CONDITIONING - ESCAPE or AIR CONDITIONING - MARINER .
Normal to low High Compressor - low performance
Additional Possible Cause Components Associated With Inadequate Compressor Operation 
  • Compressor drive belt - loose
  • Compressor clutch - slipping
  • Clutch coil open - shorted, or loose mounting
  • Control assembly switch - dirty contacts or sticking open
  • Clutch wiring circuit - high resistance, open or blown fuse
  • Compressor operation interrupted by the PCM
Additional Possible Cause Components Associated With a Damaged Compressor 
  • Incorrect clutch air-gap
  • Suction accumulator - refrigerant oil bleed hose plugged
  • Refrigerant leaks
(1) Low pressure reading will be normal to high if the pressure is taken at the accumulator and if the restriction is downstream of the access valve.
(2) Low pressure reading will be low if the pressure is taken near the compressor and the restriction is upstream of the access valve
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