DIAGNOSES — Overall System / Performance Test Diagnoses (Cont'd) — Abnormal pressure cases D, E
HA-36spec tablePerformance Test Diagnoses (Cont'd)
Trouble diagnoses for abnormal pressure — Cases D (continued) and E
Both high- and low-pressure sides are too low. [D]
Refrigerant cycleThere is a big temperature difference between expansion valve inlet and outlet while the valve itself is frosted.
Probable causeExpansion valve closes a little compared with the specification. ↓ ① Improper expansion valve adjustment ② Malfunctioning thermal valve ③ Outlet and inlet may be clogged.
Corrective action• Remove foreign particles by using compressed air. • Check compressor oil for contamination.
Both high- and low-pressure sides are too low. [D]
Refrigerant cycleAreas near low-pressure pipe connection and service valve are extremely cold as compared with areas near expansion valve outlet and evaporator.
Probable causeLow-pressure pipe is clogged or crushed.
Corrective action• Check and repair malfunctioning parts. • Check compressor oil for contamination.
Both high- and low-pressure sides are too low. [D]
Refrigerant cycleAir flow volume is not enough or is too low.
Probable causeEvaporator is frozen. ↓ Compressor discharge capacity does not change. (Compressor stroke is set at maximum length.)
Corrective actionReplace compressor.
Low-pressure side sometimes becomes negative. [E]
Refrigerant cycle• Air conditioning system does not function and does not cyclically cool the compartment air. • The system constantly functions for a certain period of time after compressor is stopped and restarted.
Probable causeRefrigerant does not discharge cyclically. ↓ Moisture is frozen at expansion valve outlet and inlet. ↓ Water is mixed with refrigerant.
Corrective action• Drain water from refrigerant or replace refrigerant. • Replace liquid tank.