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8.7 Evacuating the System
After connecting the indoor and outdoor units, evacuate the air from the line set and the indoor unit by
following the procedures below.
Leak Testing
Indoor units are nitrogen pre-charged, however they should be pressure tested before installation.
Follow the steps below to test for leaks.
1. Connect the charging hoses to the low side of the
manifold and the service port of the gas valve (See
figure beside).
2. Connect the center hose of the manifold valve to a
nitrogen source.
NOTE: The nitrogen gas cylinder is used in a vertical
standing position.
3. Charge system with nitrogen to 150 psi and check
for leaks using standard industry leak detection
methods.
4. Pay attention to possible evaporator leaks that may
have occurred during shipping or installation.
5. Remove the nitrogen by opening the manifold valves.
Vacuum Purge
1. Connect the center hose of the manifold valves to a vacuum pump, and fully open the low and high
pressure sides of the manifold valves. DO NOT open service port valves.
2. Turn on the vacuum pump. Evacuate system for about one (1) hour and confirm that the vacuum
reading is 500 microns.
3. Close all manifold valves and turn off the vacuum pump. After waiting for several minutes, confirm
that the vacuum reading of the manifold has not changed. If the vacuum reading has changed, there
is a leak that must be found and repaired before continuing.
4. Remove the valve caps from the two valves. Slowly open liquid valve completely using a hexagonal
Allen key. Use the same procedure on the suction valve. Open both valves to the full back seat
position.
5. Securely tighten the caps back onto liquid and suction valves.
6. Check for gas leaks at all connections. Test with an electronic leak detector or with soapy water. Be
sure to wipe off the soap with a clean cloth after leakage test.
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