It's sometimes difficult to tell if an inverter compressor is running or not. Sometimes I need to unplug the machine, put my hand on the compressor, then plug it back in and feel for the vibration.
The compressor in your machine is a variable speed inverter type. Your machine uses an inverter on the compressor. The inverter receives 120 VAC line-in from the power supply. The inverter converts this single-phase, 60Hz, 120 VAC into 3-phase, 80 VAC to 230 VAC, with frequency variations between 57 Hz and 104 Hz. This voltage is delivered to the compressor through 3 lead wires. Each wire will carry identical voltage and frequency. The compressor leads must be connected to measure voltage output. If the compressor wires are not connected, or if an open occurs in one of the 3 lead wires or in the compressor, the inverter will stop voltage output.
When checking inverter voltage output, connect the test-meter leads to any 2 of the 3 compressor lead wires at the inverter plug (plug should be connected). The same reading should be measured between any 2 of the 3 wires. The inverter controls compressor speed by frequency variation and by Pulse Width Modulation. Changing frequency and PWM will cause an effective voltage between 80 and 230 VAC to be received at the compressor.
There should be 120 VAC at all times between the brown wire and the orange wire on the inverter. The inverter receives a communication signal from the motherboard J15 connector at the red wire and white wire on the inverter. With all the wires connected, the output voltage from the J15 connector on the motherboard to the inverter is 4-6 VDC. If the inverter wiring is disconnected the output from J15 is 10-12 VDC. The resistance of the compressor windings is 9 to 10 ohms between any two pins on the compressor.
Note: Certain voltmeters will not be able to read voltage output from the inverter. If no voltage or erratic voltage is measured, it does not necessarily indicate a faulty inverter.