Section 7 A/C System Faults Check & Troubleshooting - Geely CK Series 2007 Workshop Manual

Section 7 A/C System Faults Check & Troubleshooting
Inspection shall be made to isolate the fault area and its cause when the fault of A/C system occurs, and then
specific service could be performed. Inspect the whole system before re-using A/C system after a long term
of storage.
First step is initial inspection by direct "see, listen and touch". Test the system with the leak detector if
necessary.
1. Check the Refrigeration System
Under the normal condition, the low pressure pipeline of the A/C refrigeration system takes on a status of low
temperature and the high pressure pipeline takes on a status of high temperature, see Figure 16. Based on
this rule, you can arrive at the initial judgement about the fault area and its cause by touching the refrigeration
system pipeline and elements to feel the surface temperature with your hand.
1
High pressure area: compressor outlet
→
condenser receiver/drier
inlet, its temperature change trend is from warm
to hot. If the temperature change is not this trend,
but instead some part is extremely hot (e.g.
condenser surface), it indcates that the part is
faulty and the radiation is not good; if some part is
extremely cold (e.g. receiver/drier) or there is frost
(e.g. at expansion valve inlet), it indicates that the
part is faulty and the pipe may be blocked.
2
Low pressure area: expansion valve outlet
→
evaporator compressor inlet, its temperature
change trend is from cool to cold, If the
temperature change is not this trend, it indcates that the part is faulty.
3
Compressor: compressor inlet and outlet high & low side shall have apparent feel of temperature difference,
if there is no temperature difference, it indicates that there is leakage in the system and the refrigerant
has leaked.
2. Check the Leakage Area
1
Observe all connecting areas of the refrigeration system or condenser surface for oil stain, if there is oil
stain, it indicates that the the refrigerant is leaking (refrigerant and freezing oil leak simultaneously,
refrigerant volatilize after leakage and leave the freezing oil remained to be oil stain).
2
Apply the soap water to the connecting area, if soap bubble occurs, it indicates that there is leakage.
3
Check with instrument, the common instrument is halogen leak detector. When using the halogen leak
detector for check, the key is the propane flame color depending on which the judgement is made. When
there is no leakage, the flame color remains unchanged, when there is a little leakage, the flame is
greenish, when there is large leakage, the flame is bluish or purple.
I. A/C System Faults Check
→
expansion valve
→
Cool
Expension
Valve
Evaporator
Compressor
Cold
Low Pressure
Figure 16 A/C System Process
Hot
Condenser
Warm
High Pressure
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