In this month’s troubleshooting situation, our customer’s description of the problem is “not cooling” and “blowing warm air,” and the equipment that is supposed to keep this residence comfortable is a split system that has been in service for 16 years. The service history of this unit includes several electrical repairs, and in one instance, a leak in the sealed system was found and repaired.

When you arrive, you find the following conditions:

• The indoor temperature is near 85°F.

• The thermostat setpoint is 70°.

• The indoor fan motor is running normally, and you determine that the indoor airflow is sufficient.

When you go to the condensing unit to continue your evaluation, you find that the outdoor fan motor and compressor are operating on this R-22 system, and, after confirming proper airflow through the condenser coil, you measure an ambient temperature of 90°. When you connect your gauges to the high and low side access valves, you read the following pressures:

• Low-side pressure: 90 psig.

• High-side pressure: 170 psig.

To complete your diagnosis, you apply the pressure readings to the temperature scales on your gauge set (see the pressure/temperature chart here for comparison) and you also measure the current draw of the compressor as lower than normal.

Your troubleshooting question: What is the specific failure that is preventing this system from cooling properly?

Compare your answers with ours by clicking on the PDF link below.

Publication date: 5/5/2014

PDF - May Troubleshooting Answer

For information on Jim Johnson’s HVACR technician training DVDs, go to www.technicaltrainingassoc.com/HVACRVideoStart.htm. 

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