In refrigeration and air conditioning systems, two common problems are a lack of refrigerant gas and a clogged capillary tube. While these issues may present similar symptoms, identifying them accurately is crucial for an effective diagnosis. Below, we detail the characteristic signs of each issue.
Before diagnosing, ensure the following:
- The evaporator is clean.
- Air filters are free from dirt.
- Adequate airflow is present in the evaporator.
1. Diagnosing a Lack of Refrigerant Gas
To confirm that the system is low on refrigerant gas, the following three mandatory symptoms must be present:
a) Low Pressure on Both Sides of the System
- The refrigerant pressure will be lower than normal on both the high-pressure and low-pressure sides.
- This can be measured using a pressure gauge while the system is running. The degree of pressure drop depends on the extent of the leak.
b) Low Compressor Amperage
- The compressor consumes less current due to the reduced amount of refrigerant to compress.
- Compare the measured current draw with the RLA (Rated Load Amperage) value indicated on the equipment.
c) Dry and Warm Capillary Tube
- When the system is running, a dry and warm capillary tube indicates proper functionality.
- If this symptom aligns with the first two, it confirms a lack of refrigerant gas.
2. Diagnosing a Clogged Capillary Tube
To identify a clogged capillary tube, check for the following mandatory symptoms:
a) Low Pressure on the Low Side and Refrigerant Accumulation in the Condenser
- A clog in the capillary tube causes refrigerant to accumulate in the condenser.
- The low-side pressure drops progressively due to insufficient refrigerant reaching the compressor, and high-side pressure also decreases as the refrigerant condenses into liquid form.
b) Slightly Low Compressor Amperage
- Reduced gas flow to the compressor’s suction side results in a slightly lower current draw than normal (RLA), though not as low as in the case of a refrigerant leak.
c) Moist or Cold Capillary Tube
- A moist or cold capillary tube, particularly towards its end, is a clear indicator of a clog.
- Conversely, a dry and warm capillary tube suggests it is functioning correctly.
d) Diagnosing in Systems with Multiple Capillary Tubes
- In systems with more than one capillary tube, if one is clogged, it will feel moist or cold, while the others remain at normal temperature. This confirms the issue lies with the specific clogged capillary tube.
