High Suction Pressure 1997 Ford Mustang 3.8

MustangThe air conditioning system has extremely high suction pressure of 250 psi and discharge pressure of 170 psi what could be the problem.


With R134a it’s common to see high side pressure between 2.2 and 2.5 times ambient temperature. On that same 80 degree day we would see between 176 and 200 PSI on the high side of an R134a system. The system operates in a specific range based on outside ambient temperature. High side pressure has a broad range relative to temperature because of heat load on the evaporator, humidity, airflow across the condenser, and engine speed.

High Suction Pressure

  • Loose expansion valve
  • Overcharged system
  • Expansion valve stuck open
  • Compressor reed valves
  • Leaking head gasket on compressor


  • Tighten valve
  • Replace reed valves
  • Remove some refrigerant
  • Replace expansion valve
  • Replace head gasket