Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Table
- Refer to the chart below.
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 pluggeda . Normal to Low Low or Clutch Cycling Low refrigerant charge, A/C suction line - partially restricted or pluggedb A/C cycling switch - sticking closed (if equipped). Erratic Operation or Compressor Not Running A/C cycling switch - poor connection at A/C clutch connector or clutch cycling switch connector. A/C electrical circuit erratic - see A/C Electrical Circuit Wiring Diagram. Refer to SYSTEM WIRING DIAGRAMS article. 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 Engine Computer
Additional Possible Cause Components 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 pressure is taken at accumulator and if restriction is downstream of service access valve.
b Low pressure reading will be low if pressure is taken near the compressor and restriction is upstream of service access valve.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.