Diagnostic Table
WARNING: This page is about a different car, the 2018 Lincoln MKT. However, it is still accessible from the selected car via links, so may be relevant.
- Use the following table to guide diagnosis of the refrigerant system if operating pressures are outside normal limits.
High (Discharge) Pressure Low (Suction) Pressure Component - Causes High Normal to High Condenser - inadequate airflow
Engine - overheatingNormal 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 (b)
Low refrigerant charge - leak in system
A/C suction line - partially restricted or pluggedErratic 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 systemAdditional Possible Components or Causes 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 engine computer
Low refrigerant charge - leak in systemAdditional Possible Components or Causes Associated With a Damaged Compressor Incorrect Clutch Air-gap
Suction accumulator - refrigerant oil bleed hose plugged
Refrigerant Leaks(a) Low pressure reading will be normal to high if restriction is downstream of service access valve. (b) Low pressure reading will be low restriction is upstream of service access valve.