Suction (Low Side) Pressure High

1. Note temperature of low pressure hose, gauge connection and evaporator. If hose and fitting are colder than evaporator, check for loose thermostat or expansion valve remaining open too long.
2. If suction pressure drops as condenser is cooled by water, check for excessive refrigerant in system.
3. Stop engine and observe pressures. If high and low side pressures equalize quickly, check for leaking head gasket, or leaking or defective high pressure valve.