DIAGNOSES — Overall System / Performance Test Diagnoses (Cont'd) — Abnormal pressure case F
HA-37spec tablePerformance Test Diagnoses (Cont'd)
Trouble diagnoses for abnormal pressure — Case F: Low-pressure side becomes negative
Low-pressure side becomes negative [F]
Refrigerant cycleLiquid tank or front/rear side of expansion valve's pipe is frosted or dewed.
Probable causeHigh-pressure side is closed and refrigerant does not flow. ↓ Expansion valve or liquid tank is frosted.
Corrective actionAfter the system is left at rest, start it again in order to confirm whether or not problem is caused by water or foreign particles. • If the problem is due to water, drain water from refrigerant or replace refrigerant. • If it is due to foreign particles, remove expansion valve and remove them with dry and compressed air. • If either of the above methods cannot correct the problem, replace expansion valve. • Replace liquid tank. • Check compressor oil for contamination.