11. NOTE: Use the following table to guide diagnosis of the refrigerant system if operating pressures are outside normal limits.
NOTE: Proper A/C system diagnosis on vehicles with Variable compressors is dependent on correct refrigerant system charge and tested in ambient temperatures above 70° F. Never replace a Variable compressor without first recovering and recharging the A/C system to vehicle specification and retesting in ambient temperatures above 70° F.
Refer to the chart below.
High (Discharge) Pressure | Low (Suction) Pressure | Component — Causes |
|---|---|---|
High | Normal to High | Condenser — inadequate airflow. Engine — overheating. |
Normal to High | Normal | Refrigerant overcharge — air in refrigerant. |
Normal to Low | High | A/C Compressor — low performance. |
Normal to Low | Normal to High | A/C suction line — partially restricted or plugged. a |
Normal to Low | Low | Low refrigerant charge — leak in system. A/C suction line — partially restricted or plugged. b |
Erratic Operation or Compressor Not Running | Ambient Air Temperature (AAT) sensor — poor connection. A/C pressure transducer — poor connection. Evaporator temperature sensor — poor connection. Low refrigerant charge — leak in system. | |
Additional Possible Components or Causes Associated With Inadequate Compressor Operation | ||
Compressor drive belt — loose Compressor clutch — slipping Clutch coil open — shorted, or loose mounting
2016 Mustang workshop publication supplied to Mustang Atlas. Original technical text and illustrations; HTML formatting by Mustang Atlas. Source page numbering is retained for traceability. Follow the configuration, revision, warnings, and cross-references in the material. About this edition.