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7) Evacuation, Vacuum Pump and Refrigerant Charge [R134a]
Never allow the oil in the vacuum pump to flow backward. The vacuum level and
vacuum pump may be the same as those for the current refrigerants. However, the
rubber hose and gauge manifold to be used for evacuation and refrigerant charge
should be exclusively for R134a.
8) Refrigerant Leak Check
Refrigerant leaks can be detected by charging the unit with a little refrigerant, raising
the pressure with nitrogen and using an electronic detector. Do not use air or oxygen
instead of nitrogen for this purpose, or rise in pressure as well as in temperature may
cause R134a to suddenly react with oxygen and explode. Be sure to use nitrogen to
prevent explosion.
[b] REFRIGERANT RECOVERY
The refrigerant must be recovered in methods in compliance with the European F-gas
regulation. Recover the refrigerant from the access valve, and store it in a proper
container. Do not discharge the refrigerant into the atmosphere. This is a fineable
offence.
When replacing the drier, take the opportunity to also fit a high-side access valve for
ease of charging liquid refrigerant.
Note: Replacement refrigerant may not be available for sale due to the phase-out under
the European F-gas regulation.
[c] EVACUATION AND RECHARGE
1) Attach charging hoses, a service manifold and a vacuum pump to the system. If
possible, use quick release connectors onto the access valves (especially on the
high side).
2) Turn on the vacuum pump.
3) Allow the vacuum pump to pull down to a 760 mmHg vacuum. Evacuating period
depends on the pump capacity.
4) Close the low-side and high-side valves on the service manifold.
5) Disconnect the vacuum pump, and attach a refrigerant charging cylinder to
accurately weigh in the liquid charge. Remember to purge any air from the charging
hose. See the nameplate for the required refrigerant charge.
