- 1). Use the multimeter to check that the correct voltage is being supplied to the compressor. Switch on the system. Check the voltages at the motor terminals and at any sensors or valves which are connected to the power supply. Check for current in the main connecting cable. Replace the motor if the correct voltage appears at the motor, valves and sensors but no current flows. If current is flowing, measure it with the multimeter.
- 2). Compare the measured current with the rated current on the motor nameplate. If the current is high, at many times the rated current, replace the motor because it has a short circuit. If the current is between the rated current and six times the rated current, check for an obstruction, a seized bearing, mechanical damage or internal debris which may be preventing the motor or compressor from turning normally.
- 3). Check for other damage if the motor current is close to the rated current because the motor and compressor are turning normally. Check the piping for leaks. Check the filters and valves for obstructions. Check the pressures before and after the compressor with the pressure gauge and compare to the normal values. Check the compressor oil for contamination. If the pressure before the compressor is normal and the pressure after the compressor is low, the compressor has internal damage. If the oil shows foam or a soapy film, the compressor has an internal leak. In both cases, replace the compressor or send it out for repair.
previous post