System Checking With the Manifold Gauge Set

R134A System Checking With Manifold Gauge Set





Evacuating the Manifold Gauge Set
Attach the center (service) hose to a vacuum pump and start the pump. Open fully both high and low valves and allow the vacuum to remove air and moisture from the manifold set for at least five minutes. Turn the vacuum pump off and isolate it from the center service hose but do not open the hose to atmosphere.

CAUTION: It is imperative that the vacuum pump is not subjected to a positive pressure of any degree, therefore the pump must be fitted with an isolation valve at the center (service hose) connection. This operation replaces the "purge" procedure used on previous systems. Observe the manufacturers recommendation with regard to vacuum pump oil changes.

Connecting the Manifold Gauge Set

CAUTION: Only use hoses with connectors which are dedicated to HFC 134A charge ports.

Attachment of the hose quick release connectors to the high and low side system ports is straightforward, provided that the high and low valves are closed and the system is not operational.

WARNING: Under no circumstances should the connections be made with the system in operation or the valves open. Should the valves be open and a vacuum pump or refrigerant container attached, an explosion could occur as a result of high pressure refrigerant being forced back into the vacuum pump or container.

NOTE: Assessment of system operating efficiency and fault diagnosis may be achieved by using the facilities on your Recovery/Recharging/Recycling station, follow the manufacturers instructions implicitly and Observe all safety considerations.

Stabilizing the System
1. Accurate test gauge data will only be attained if the system temperatures and pressures are stabilized.
2. Ensure that equipment and hoses cannot come into contact with engine moving parts or sources of heat.





3. It is recommended that a free standing air mover is placed in front of the vehicle to provide mass air flow through the condenser/cooling system.
4. Start the engine, allow it to attain normal working temperature and set at fast idle (typically 1200 to 1500 RPM).
5. Select full air conditioning performance by pressing the MAX control button.
6. With all temperatures and pressures stable or displaying symptoms of faults, begin relevant test procedures.

System Fault Diagnosis





Probable causes of faults may be found by comparing actual system pressures, registered on your manifold gauge set or recovery/recharge /recycle station, and the pressure/temperature relationship graphs. The chart shows the interpretation that may be made by this difference. The "Normal" condition is that which is relevant to the prevailing ambient and evaporator temperatures.

NOTE: If erratic or unusual gauge movements are experienced, check the equipment against a known manifold gauge set.