HIGH COMPRESSOR INVERTER TEMPERATURE

HIGH INVERTER TEMPERATURE



High inverter temperature alarms/ faults on an air cooled unit is frequently an indicator of low charge. 

On an air cooled chiller, the control of the expansion valve attempts to maintain the liquid level in the evaporator in accordance with the liquid level setpoint.  In the case where refrigerant charge is lost from the chiller, the liquid refrigerant ¨seal¨ in the liquid line will be lost and the compressor will begin to experience high inverter temperatures due to reduced liquid available in the compressor cooling connection.

In this case, bubbles will be observed in the motor cooling line sightglass. 

This can be temporarily resolved by lowering the liquid level setpoint, which will back up liquid in the liquid line, restoring sufficient liquid to the compressor motor cooling line.

Other possible causes could be a problem with the temperature sensor itself, the cooling solenoid on the compressor or the relay in the Serial card that controls the cooling solenoid.

Trouble shooting on this depends a lot on if there are multiple compressor available, or only a single compressor.  With multiple compressor, you can change out components to identify where the problem lies.

Under normal circumstances, with the compressor running, watching the reading from the inverter temperature sensor, you will see the temperature rise until the cooling solenoid opens, then the temperature will fall until the cooling solenoid closes.  This cycle will repeat continuously. 

There are LED´s on the backplane that indicate if the cooling solenoid is energized.  These LED´s can give an indication to the service technician if the problem is with the solenoid if they are lighting up but the solenoid is not energizing.  On the other hand, if the lights on the backplane are not lighting up, the problem can be with the relay in the Serial Card, or with the inverter temperature sensor itself.