!
WARNING:
Cancer
and Reproductive Harm
www.P65Warnings.ca.gov
41
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 different systems and conditions have different
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 flashing. Condition
indicated by an extreme differential 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 flow 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 flooding 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
