AI Diagnostic Report
Most Likely Issues
1. Low Refrigerant Charge
2. High Superheat
3. Restricted Metering Device
Why These Issues Are Likely
1. Low Refrigerant Charge: The system is not cooling properly, and the suction pressure is relatively low (65 PSI) compared to the head pressure (425 PSI). This could indicate a low refrigerant charge, which would prevent the system from functioning efficiently.
2. High Superheat: The calculated superheat is 25°F, which is higher than the typical range of 5-10°F. This could indicate that the refrigerant is not being properly cooled in the evaporator coil, which could be due to a low refrigerant charge or a restricted metering device.
3. Restricted Metering Device: The high superheat and low suction pressure could also indicate that the metering device (such as an expansion valve) is restricted, which would prevent the refrigerant from flowing properly through the system.
Step-By-Step Next Tests
1. Measure temperature drop across filter drier: Check the temperature drop across the filter drier to ensure it's functioning correctly.
2. Inspect evaporator coil for ice or dirt: Inspect the evaporator coil for any signs of ice or dirt buildup, which could be restricting airflow and causing high superheat.
3. Check return/supply delta T: Measure the temperature difference between the return and supply air to ensure it's within the expected range.
4. Measure voltage under load at the contactor: Check the voltage at the contactor under load to ensure it's within the expected range.
5. Ohm out compressor windings with power off: Measure the resistance of the compressor windings with power off to ensure they're not shorted or open.
6. Verify airflow and static pressure: Verify that the airflow and static pressure are within the expected range for the system.
Recommended Repair Actions
* If the system is found to have a low refrigerant charge, recharge the system to the recommended level.
* If the metering device is restricted, replace it with a new one.
* If the evaporator coil is dirty or iced up, clean or replace it as needed.
* If the temperature drop across the filter drier is not within the expected range, replace the filter drier.
Safety Warnings
* Always lockout/tagout and disconnect power before opening panels or testing components.
* Wear proper PPE for refrigerant handling, including gloves, safety glasses, and a face mask.
* Ensure good ventilation when dealing with refrigerant leaks to prevent inhalation of refrigerant vapors.
* Follow manufacturer instructions and local codes for all repairs and testing.