Blown valve plate or cylinder head gasket - Replace valve reeds or cylinder head gaskets or plates.
Broken suction or discharge valve reeds - Replace broken reeds
Compression ration too high
a. verify proper settings of high and low pressure switches.
b. Inspect for condenser plugging.
c. Ensure all evaporator and condenser fan are operating properly
High suction temperature - Reduce suction temperature by expansion valve adjustment or provide desuperheating.
Cylinder head cooling fan not operating or incorrect voltage for fan motor. - Replace defective parts or verify available voltage agrees with fan motor voltage.
Non seating internal air pressure valve - Check for signs of overheating replace if necessary.
High oil level - Low oil level
Excessive blow by into crank-case worn rings, valve reeds or blown gaskets. - Replace gasket, valve reeds, and plates or rebuilt compressor.