Bard Tech Tip #4.1 - Electronic Expansion Valve (EEV) Tool - Having The Right Tool For The Job.

If your unit has an EEV (Electronic Expansion Valve) it’s important that you have the proper equipment to service the refrigeration system.

Electronic Expansion Valve Operation: This model employs an electronic expansion valve (EEV) which meters the refrigerant to the evaporator.
In the heat pump application, the EEV is used bidirectionally to meter the refrigerant in both heating and cooling modes. The EEV is made of a stepper motor that is controlled with a step output from the controller. The valve is capable of 480 steps which drives a needle valve that in turn regulates the flow of refrigerant. The EEV allows for tighter control and
better capacity management in varying operating conditions than a standard TXV. The EEV system consists of the electronic valve and stator, control board, relay, suction temperature sensor and suction pressure transducer. The pressure transducer and temperature sensor monitor the suction line to provide real time data to the control board so that a real time
superheat can be calculated. This then determines the EEV position. The controller is sent to maintain around 13° superheat. The relay is used to activate the EEV system’s controller anytime that the compressor is energized.

EEV Instructions for Vacuuming, Reclaiming and Charging Unit: The electronic expansion valve moves to a closed position when there is no call to control. In order to pull a complete vacuum, fully reclaim the system or
charge the unit, connections to both the suction and discharge service ports need to be utilized or the valve needs to be manually opened first. The valve can be opened manually using the magnetic EEV service tool (Bard Part # 2151-021) shown in Figure 1. To do this, remove the EEV stator coil (red color with retaining nut on top), slide the magnetic tool over the shaft
where the stator was removed and turn in a clockwise direction to open the valve to the full open position (directional arrows are provided on the tool).
Reapply the EEV stator coil and retaining nut once complete. Upon powering the unit back up, the control board will automatically drive the EEV back to the fully shut position. Once the compressor starts, the control board will again modulate the EEV position to control the system superheat.

See Bard document 7960-828 for additional trouble shooting information.

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