Mastercool R134a Digital Manifold - Manual (Page 3)

3
NOTE: Be sure that the hand valves on the manifold gauge set are in the
closed position. Always wear gloves and safety goggles when working with
refrigerant.
1. Remove the protective caps from the system ports. Check for leaks at the
ports.
2. Connect the Low side service hose (Blue) to the suction side of the
compressor. Connect the High side service hose (Red) to the discharge side of
the compressor. Make sure the couplers are securely snapped.
3. If using manual couplers, move the plunger down within the coupler by turning
the knob clockwise in order to open the port valves and start refrigerant flow.
IMPORTANT NOTES
A system that has been opened or one that is found to be excessively low on
refrigerant pressure as a result of a leak, must be fully evacuated by means of
recycling and deep vacuum.
A system that has been evacuated must be repaired, leak tested and evacuated
before charging. If charging on the liquid or High side, use only the High side
valve on the manifold gauge set. Make sure the Low side valve is closed. After
charging, test the system by turning on the engine and running the A/C with
both valves closed on the manifold. After testing, disconnect the couplers from
the system and make sure to use a recovery/recycling machine to evacuate any
refrigerant remaining in the hoses.
DIAGNOSING TIPS FOR THE A/C SYSTEM
• Low side and High side pressures are low. Usually indicates a low charge.
• Low side pressure is low and High side pressure is high. Usually indicates a
blockage in the system. (i.e. expansion of valve or orifice tube.)
• Low side pressure is high and High side pressure is low. When accompanied
by a fluctuating digital reading, usually indicates faulty reed valves in
compressor.
• Low side and High side pressures are high. Usually indicates an over charged
system.
R134a TEMPERATURE PRESSURE CHART
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BAR PSI N-Hg MPa Kg/cm 2 BAR PSI MPa Kg/cm 2
High
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Low
Ref.Cap.:2.70 LBS OIL.Cap.:11.00 oz
Ambient Temperature (˚F) Low Side Gauge High Side Gauge
65˚ 25-35 psi 135-155 psi
70˚ 35-40 psi 145-160 psi
75˚ 35-45 psi 150-170 psi
80˚ 40-50 psi 175-210 psi
85˚ 45-55 psi 225-250 psi
90˚ 45-55 psi 250-270 psi
95˚ 50-55 psi 275-300 psi
100˚ 50-55 psi 315-325 psi
105˚ 50-55 psi 340-345 psi
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