AC–73 AIR CONDITIONING SYSTEM – TROUBLESHOOTING 4. POOR CIRCULATION OF REFRIGERANT Condition: insufficient cooling N04150 Symptom seen in refrigeration system | Probable cause | Diagnosis | Remedy • Pressure low on both low and high pressure sides • Frost on tubes from receiver to unit | • Refrigerant flow obstructed by dirt in receiver | • Receiver clogged | • Replace receiver 5. REFRIGERANT DOES NOT CIRCULATE Condition: Does not cool (Cools from time to time in some cases) N04160 Symptom seen in refrigeration system | Probable cause | Diagnosis | Remedy • Vacuum indicated on low pressure side, very low pressure indicted on high pressure side • Frost or dew seen on piping before and after receiver/drier or expansion valve | • Refrigerant flow obstructed by moisture or dirt in refrigeration system • Refrigerant flow ob–structed by gas leakage from expansion valve heat sensing tube | • Refrigerant does not circulate | (1) Check heat sensing tube, expansion valve and ERP (2) Clean out dirt inexpan–sion valve by blowing with air If not able to remove dirt, replace expansion valve (3) Replace receiver (4) Evacuate air and charge new refrigerant to proper amount. for gas leakage from heat sensing tube, re place expansion valve.