FATC 41 e. REFRIGERATION CYCLE TROUBLESHOOTING Sr. No. Problem Possible Cause Remedy 4 Refrigerant fails to circulate Condition 29. Air conditioner does not cool. Symptoms in refrigerant cycle 30. Pressure on the low pressure side is vacuum 31. Pressure on the low pressure side is vacuum low. 32. Frost or dew is formed on the piping at the front and rear side of the receiver or the expansion valve. Cause 33. Moisture or dirt in the refrigerating cycle freezes or sticks to the expansion valve orifice, obstructing refrigerant flow. 34. Gas leaking from the heat sensitizing tube of the expansion valve obstructs refrigerant flow. Diagnosis 35. Blocked expansion valve orifice. Countermeasures 36. Allow to stand for some time and then resume operation to decide whether the blockage is caused by moisture or by dirt. If caused by moisture; remove the moisture by evacuation, Recharge new refrigerant to the specified amount. 37. If cased by dirt; remove the expansion valve and blow out the dirt with compressed air. If unable to remove the dirt, replace the expansion valve. Evacuate and charge new refrigerant to the specified amount. If caused by gas leaking from heat sensitizing tube, replace the expansion valve. 5 Expansion valve malfunctioning (opening too much) and improper installation of heat sensitizing tube. Condition 38. Air conditioner does not cool effectively. Symptoms in refrigerant cycle 39. Pressure on both the low and high. pressure sides is high. 40. Frost or heavy dew is formed on the piping on the low pressure side. Cause 41. The expansion valve is malfunctioning or the heat sensitizing tube is improperly installed. 42. Flow control is not properly performed Diagnosis 43. Excessive liquid refrigerant in the low pressure side piping. 44. Expansion valve opened too far. Countermeasures 45. Check the installation of the heat sensitizing tube. 46. If the installation is proper, replace the expansion valve. 6 Faulty compression of compressor Condition 47. Air conditioner does not cool. Symptoms in refrigerant cycle 48. Pressure on the low pressure sides is too high and pressure on the high pressure side is too low. Cause 49. There is leakage in the compressor Diagnosis 50. Faulty compression of compressor. 51. Delivery valve or packing is leaking or broken or compressor is malfunctioning. Countermeasures 52. Check the compressor oil for contamination and quantity. 53. place the compressor.
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