Since most refrigeration equipment tends […] If the evaporator is either slightly cool or not cold at all, and your compressor is running constantly (not short-cycling; see section 4-9) you have a more serious problem. Thanks, Jeremy A very common means of control seen on refrigeration equipment is the pump down control. Compressor. Understanding Reasons For AC Compressor Not Working But Fan Is Running. What is an HVAC Compressor? Since these are old units, they will use R22 as the refrigerant. Its role is to carry heat out of the house while compressing the refrigerant fluid. If the compressor is not working, the refrigerator won’t cool. Excessive liquid refrigerant returning to the compressor (flood back). The compressor is a pump which compresses the refrigerant and circulates the refrigerant through the evaporator and condenser coils. If the evaporator fan does not work or kick on when the compressor does, your unit will not be able to produce cool air. If the motor is immersed in liquid refrigerant they can show higher level of leakage current. The compressor is an integral part of the air conditioning system. Pump down control stops off cycle migration of refrigerant to any part of the system, including the compressor’s crankcase, which, we will see later, can cause lack of proper lubrication. A compressor in trouble is not able to pump refrigerant through the system, resulting in a lack of cooling power. Then obtain the pump curve for that specific model pump and im-peller diameter (see the next section). charge side of the pump during operation and compare with the vessel’s pressure to determine that the pump is developing a pressure rise and note the magnitude (estimated by differ-ence between the gauge reading and the vessel pressure). Before replacing the compressor, first check all … This article is written by Jeremy Smith CM, experience refrigeration tech and all-around great dude. The evaporator fan is the part of the fridge that blows the cool air you feel when you open the door. However, this is rarely the case. Defective oil pump or the oil pump inlet screen is restricted. Air Conditioning and Cooling Systems - Carrier A/C - Compressor running but not pumping - Hi all, I have a Carrier Heat Pump (3 ton), which is about 11 … The system should be run for a brief period of time before the hipot test is conducted. The warmed refrigerant is heated up further, which converts it from its gaseous state into liquid. On the next start-up, this liquid mixture will return to the compressor as a slug. Scroll compressors are configured with the motor on bottom and the pumping components at the top. However, it’s important to note that this symptom can also be caused by a refrigerant … The same diagnosis applies if just the first coil or two in the evaporator is (are) frosted and the … The refrigerator compressor is both a motor and a pump that move the refrigerant through the system. Using a “pump down” system of control can prevent this condition. Temperature sensors signal the compressor to start when the temperature inside the refrigerator rises above its set point. Why do we use this rather than just cycling the compressor off and on like a residential HVAC unit? It pulls air across the evaporator coil, cooling it, and then pushes the air through the freezer and refrigerator. Crankcase heater not installed or defective (migration).