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Service Manual VMH SerieS Heat Controller, Inc.
11
7.4 Installation for the first time
Air and moisture in the refrigerant system have undesirable effects as indicated below:
● Pressure in the system rises.
● Operating current rises.
● Cooling or heating efficiency drops.
● Moisture in the refrigerant circuit may freeze and block capillary tubing.
● Water may lead to corrosion of parts in the refrigerant system.
Therefore, the indoor units and the pipes between indoor and outdoor units must be leak tested and
evacuated to remove gas and moisture from the system.
Gas leak check (Soap water method):
Apply soap water or a liquid neutral detergent on the indoor unit connections and outdoor unit
connections with a soft brush to check for leakage on the connecting points of the piping. If air bubbles
come out, the connections have leaks and those connection points must be tightened. Recheck to
ensure all leakage points are tightened properly and not leaking.
1. Air purging with vacuum pump
1) Completely tighten the flare nuts of the indoor and outdoor units, confirm that both the 2-way and
3-way valves are set to the closed position.
2) Connect the charge hose with the push pin of handle lo to the 3-way valves gas service port..
3) Connect the charge hose of handle hi connection to the vacuum pump.
4) Fully open the handle Lo of the manifold valve.
5) Operate the vacuum pump to evacuate.
6) Conduct evacuation for 30 minutes and check whether the compound meter indicates -0.1Mpa. If
the meter does not indicate -0.1Mpa after pumping 30 minutes, it should be pumped 20 minutes more. If
(Indoor unit)
(Liquid side)
(Gas side)
Vacuum
pump
Vacuum
pump
Lo
Hi
Handle Hi
Two-way valve
Close
Manifold valve
Compound meter
Pressure
gauge
-0.1MPa
Handle Lo
Charge hose
Charge hose
(Outdoor unit)
Close
Three-way valve