ESIE05-04 Additional Checks for Troubleshooting
Part 3 – Troubleshooting 3–59
4.7 Evaluation of Abnormal Low Pressure
Abnormally low pressure level is mostly caused by the evaporator side. The following contents are
provided based on field checking of service engineer. Further, the number is listed in the order of
degree of influence.
In cooling operation
In heating operation
Check items (Possible causes) Judgment
Does the outdoor unit fan run normally? Visual inspection
Is the indoor unit filter clogged? Visual inspection
Is there clogging before or after the EV (capil-
lary)?
Check if there is a temperature difference
before and after EV (capillary).
Check if the main valve unit of EV operates (by
noise, vibration).
Is the check valve clogged?
*Heat pump model only
Check if there is a temperature difference
before and after check valve.
→ If YES, the check valve is caught.
Is the LPS normal? Check continuity using a tester.
Is the indoor unit installed under such conditions
that short circuit easily occurs?
Visual inspection
Is the refrigerant gas short? Conduct refrigerant collection and vacuum dry-
ing, and then add proper amount refrigerant.
Check items (Possible causes) Judgment
Does the outdoor unit fan run normally? Visual inspection
Is the outdoor unit heat exchanger clogged? Visual inspection
Is the outdoor unit installed under such condi-
tions that short circuit easily occurs?
Visual inspection
Is there clogging before or after the EV (capil-
lary)?
Check if there is a temperature difference
before and after EV (capillary).
Check if the main valve unit of EV operates (by
noise, vibration).
Is the check valve clogged? Check if there is a temperature difference
before and after check valve.
→ If YES, the check valve is caught.
Is the LPS normal? Check continuity using a tester.
Is the refrigerant gas short? Conduct refrigerant collection and vacuum dry-
ing, and then add proper amount refrigerant.
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