Nordic ATWC Series, Инструкция по установке и обслуживанию, Страница: 67 / 106

PRELIMINARY: 24-Sep-2021 Page 67 002536MAN-00
EEV TROUBLESHOOTING
If there is a refrigeration problem such as low charge, plugged filter-dryer, EEV stuck, or any other kind of restriction in
the refrigeration system, the apparent EEV position will work its way towards 100% (full open). High superheat is also a
symptom.
If an EEV is not working and is stuck partway open, the apparent EEV position will work its way either to 100% or to the
10% minimum.
If there is low suction and the EEV position is also low then the problem is generally not in the refrigeration system;
check the water or air flow of the indoor or outdoor loop, whichever is currently being used as the source (evaporator).
To determine if an EEV is working, use the PC APP and put the system in manual override mode. Manually adjust the
EEV position by at least 25% either up or down and check to see that the suction pressure, discharge pressure and su-
perheat react to the change. If there is no reaction, then it is likely that the EEV is not working or is stuck. There are 3
possibilities: the control board is not working properly, the cable is faulty, or the EEV is faulty.
Set the EEV back to AUTO and then turn the heating or cooling demand off (but leave power on). Once the demand is
off, if the EEV is working then the discharge pressure should remain significantly higher than the suction pressure, i.e.
the system will not equalize (since EEV’s are closed when there is no demand). If the system does equalize it is likely
that the EEV is not working and is partially open. Manually set the EEV to 25% and wait for it to stop. Set the EEV to –
1, this will cause it to overdrive. You should hear the valve clicking and then the clicking should change and get louder
when the valve bottoms out.
If there is no clicking sound then either the control board is faulty, or the cable is faulty. The simplest method to check
this is to connect a new EEV and cable to the control board and visually check the EEV so see if it opens and closes by
setting the position o 0 and 100% If the new EEV works then the EEV in the unit needs to be replaced.
1) Connect a test EEV and test cable to the control board.
2) Set the EEV position to 0%.
3) Set the EEV position to 100% and then listen for clicking and watch to see if the pintle in the EEV moves open.
4) Set the EEV position to 0% and then listen for clicking and watch to see if the pintle in the EEV moves closed.
5) If the EEV does not move in one or both directions then the control board must be replaced.
6) If the test EEV moves in both directions then then either the cable or the EEV in the unit is faulty.
7) Disconnect the test EEV from the test cable and connect it to the cable in the unit.
8) Repeat steps 2 to 4.
9) If the test EEV moves in both directions then the EEV in the unit is faulty and must be replaced.
10) If the test EEV does not move in one or both directions then the cable must be replaced.