2. Leak test all refrigerant piping connections including the service port flare caps to be sure
they are leak tight. Do not over-tighten the refrigerant piping connections: tighten between
40 in-lb and 60 in-lb maximum.
3. Release the nitrogen charge.
4. If refrigerant leaks are present, repair the leaks and repeat Step 1 to Step 4 as needed until
the testing indicates that no refrigerant leaks are present.
Evacuating the refrigerant lines and indoor coil
About this task:
Evacuate the system to 500 microns or less. If a leak is suspected, leak test with dry nitrogen to
locate the leak. Repair the leak and test again.
To verify that the system has no leaks, do the following steps:
1. Close the valve to the vacuum pump suction to isolate the pump and hold the system under
vacuum.
2. Watch the micron gauge for a few minutes.
a. If the micron gauge indicates a steady and continuous rise, it is an indication of a leak.
b. If the gauge shows a rise, then levels off after a few minutes and remains fairly constant,
it is an indication that the system is leak free but still contains moisture and may require
further evacuation if the reading is above 500 microns.
Note: If compressors or compressor oils are to be removed, ensure that they have been
evacuated to an acceptable level to make certain that flammable refrigerant does not
remain within the lubricant. The compressor body shall not be heated by an open flame
or other ignition sources to accelerate this process. When oil is drained from a system, it
must be carried out safely.
CAUTION
Ensure that the outlet for the vacuum pump is not near potential ignition sources, and have
ventilation available.
What to do next:
Recover the refrigerant and adhere to the following rules:
• Ensure that the recovery equipment is in good working order and suitable for recovering
flammable refrigerants.
• Always recover the refrigerant charge into the correct recovery cylinders.
• Ensure that cylinders are labeled for the recovered refrigerant, and they have pressure-relief
valves and working shut-off valves.
31Installation Manual: R-454B Outdoor Split-System Air Conditioner
Johnson Controls Ducted Systems
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