Barko 830B, Руководство по обслуживанию

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26-8
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SERVICE- HVAC SYSTEM
(continued...)
1.2.5 Diagnosing an Expansion Valve System
Refrigerant Pressure Diagnosis-
Use the chart below to help diagnose air conditioning problems in an
expansion valve system.
5-30 PSI 150-285 Clear – any color other than Cold – Lines sweating 40
o
– 50
o
Pressure will be Low air flow past white or clear indicates heavily, no frost
Higher at higher the condenser system contamination
blower speeds increases high side
pressures
System Operating Normally – Fully Charged
Diagnostic Chart
Low Low Poor or no cooling Low or improper refrigerant Check and repair any leaks
5-30 PSI 110-150 PSI Foamy bubbles in the sight charge. in the system.
glass. Compressor cycles Recharge system as needed.
rapidly. Warm evaporator
outlet line.
Low or Vacuum. Low to Normal. No cooling. Low or improper refrigerant Check the expansion valve
-20 to 5 PSI 115-160 PSI Sight glass is clear. Bad expansion valve. and screen.
Warm evaporator outlet line. Gauge reading may be Look for icing on the
Higher if the restriction is high-side lines.
directly past service fitting. Clear the restriction or
replace necessary
components. Evacuate and
recharge the system.
Normal to Low. Normal Unit works fine for a while, Evaporator freeze-up. Replace thermostatic switch,
0-25 PSI 150-285 PSI then begins to blow warm air. Bad thermostatic switch, clutch or clutch relay.
Evaporator pipes frozen. clutch or clutch relay.
Compressor doesn’t cycle.
High or Equal to Low or Equal to No cooling. Expansion valve stuck open. Repair or replace
High Side gauge. Low Side gauge. Warm evaporator outlet pipe. Bad compressor. compressor.
70-90 PSI 90-110 PSI Compressor won’t cycle. Replace expansion valve.
Evacuate and recharge the
system.
Normal to High. High Fair to poor cooling System overcharged. Recover excess R12 or R134a
30-60 PSI 250-350 PSI Sight glass clear to foamy. until system operation
Evaporator outlet cool to returns to normal.
warm.
Normal to High. High Fair to poor cooling. Restricted airflow past Check cooling fan operation.
30-60 PSI 250-400 PSI Sight glass clear. Condenser. High Clear radiator or condenser
Evaporator outlet cool to temperature air across restriction. Check for excess
warm. condenser heat load if near hydraulic oil
cooler, etc.
Low Side
Low Side
High Side
High Side
Sight Glass
Symptoms
Evaporator Outlet
Diagnosis
Duct Temp
Solutions
05/31/2019
Updated
SERVICE