Page 1519 - Foton Workshop Manual - Auman EST-M

Electrical system – electrical components EL - 95

Phenomenon Possible reason Diagnosis Measure IN
Both low pressure side and high
● Check and replace the
pressure side are at high ● Too much refrigerant in the
expansion valve DI
pressures. Frost or much The expansion valve lower pressure tubing.
● Ensure the amount of the
condensate is formed on the failures ● The expansion valve is
refrigerant in the system meet
tubings of the high pressure and contaminated or blocked.
specified value. EG
low pressure sides
● The compressor failures (condition: no refrigeration)
TR

AX

FR

ST

BR

BW
Phenomenon Possible reason Diagnosis Measure
The pressure of the low
● Compressor failure. EL
pressure side is too high while Internal leakage of the Repair or replace the
● leakage at the damaged
the pressure of the high pressure compressor compressor
valve body or moving parts.
side is too low.

2. Check leakage with soap solution

When detecting major leakage at the refrigeration tubing connections, soap water can be sprayed around the
connection to see if bubble occurs This method is relatively simple and convenient, but the minor leakage may
not be detected.

3. Non-selective detector
This detector can detect leakage of a variety of liquid or gas, regardless of the chemical composition of the
material to be test. It features in advantages of easy to use, stable performance, low price and so on. But it can

not be used for regional testing.
4. Halogen leak detector
With a specific sensor, it can detect trace amounts of fluorine, chlorine, bromine, iodine compounds contained
in air without interference from other substances. Its biggest advantage is the high sensitivity. It can

effectively reduce false report. For regional detection, its minimum detection limit is less than 5g (per year);
for point detection, the limits below 1.5g (per year).
5 Special electronic leak detector

This instrument is complex and expensive, It can sensitively detect a particular compound without
interference from other substances. Such as the R-134a-specific detector, its sensitivity and selectivity are
high. It can not only detect leaks accurately, and also identify whether the refrigerant is R-134a or not. When

using this instrument, attention is required to consider the pollution of surroundings, otherwise, false report is
liable to be generated.
6. Fluorescent leak detection
Fluorescents produce fluorescence when exposed to ultraviolet light. Therefore, if this type fluorescents has

been added into refrigeration oils or refrigerants, when leakage occurs in the system, the leak point of the
system can be clearly found under the radiation of the UV light.

EL-095