TATA PUNCH-SERVICE MANUAL

HVAC 26 e. REFRIGERATION CYCLE TROUBLESHOOTING Sr. No. Problem Possible Cause Remedy 4 Refrigerant fails to circu- late Condition  Air conditioner does not cool. Symptoms in refrigerant cycle  Pressure on the low pressure side is vacuum  Pressure on the low pressure side is vacuum low.  Frost or dew is formed on the piping at the front and rear side of the receiver or the expansion valve. Cause  Moisture or dirt in the refrigerating cycle freezes or sticks to the expansion valve orifice, obstructing refrigerant flow.  Gas leaking from the heat sensitizing tube of the expansion valve obstructs re- frigerant flow. Diagnosis  Blocked expansion valve orifice. Countermeasures  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.  If cased by dirt; remove the expansion valve and blow out the dirt with compressed air. If unable to remove the dirt, re- place the expansion valve. Evacuate and charge new re- frigerant to the specified amount. If caused by gas leak- ing from heat sensitizing tube, replace the expansion valve. 5 Expansion valve mal- functioning (opening too much) and improper in- stallation of heat sensitiz- ing tube. Condition  Air conditioner does not cool effectively. Symptoms in refrigerant cycle  Pressure on both the low and high. pres- sure sides is high.  Frost or heavy dew is formed on the pip- ing on the low pressure side. Cause  The expansion valve is malfunctioning or the heat sensitizing tube is improperly in- stalled.  Flow control is not properly performed Diagnosis  Excessive liquid refrigerant in the low pressure side piping.  Expansion valve opened too far. Countermeasures  Check the installation of the heat sensitizing tube.  If the installation is proper, re- place the expansion valve. 6 Faulty com- pression of compressor Condition  Air conditioner does not cool. Symptoms in refrigerant cycle  Pressure on the low pressure sides is too high and pressure on the high pressure side is too low. Cause  There is leakage in the compressor Diagnosis  Faulty compression of compressor.  Delivery valve or packing is leaking or broken or compressor is malfunctioning. Countermeasures  Check the compressor oil for contamination and quantity.  Replace the compressor.