Broce FMJ470 - A;C System Troubleshooting; A;C Troubleshooting Chart

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BROCE FMJ470
Troubleshooting Chart
The following chart lists some of the common problems that plague A/C systems
and refer them to the pressure readings on your test gauges. They are referred to
as “low” or “high” due to the fact that di󰀨erent systems and conditions have di󰀨erent
normal readings.
SUCTION DISCHARGE POSSIBLE PROBLEM
LOW HIGH
1. Restriction between the discharge of the com-
pressor and inlet of receiver drier. Check
condenser and condenser lines for a point of
restriction that may create ashing. Condition
indicated by an extreme di󰀨erential in temperature
at the point of restriction.
LOW LOW
1. Possible restriction between drier and suction
side of compressor.
2. Low refrigerant charge _ bubbles in sight glass.
3. Restriction at drier or expansion valve _ sight
glass usually clear.
HIGH HIGH
1. Air in system.
2. Overcharged system (oil or refrigerant).
3. Condenser fan not working.
4. Air ow restriction on condenser
HIGH LOW
1. Weak compressor _ indicated by accelerating
the engine and watching the suction and discharge
readings. Normally, suction moves lower and dis-
charge side should rise.
2. Expansion valve ooding or stuck open _ this
would cause high and low sides to become less
distinguishable.
ATTENTION
R-134a A/C Refrigerant Factory Charge:
John Deere = 3.0 lb (1.36kg)
Ester Oil Change:
Compressor = 8.0 oz
System = 4.0 oz
MAINTENANCE
TROUBLESHOOTING- A/C SYSTEM