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Page 8 GSM-01 081310
Installing the Evaporator Unit
Please refer to the supplied Unit Specic Installation Guide
for detailed evaporator installation guidelines.
Head Pressure Control, Low Ambient Control Switch, Fan Cycling Switch:
These switches are used to cycle the condenser fan at low ambient temperature conditions. If your unit is
equipped with a Low Ambient Control, set the switch to 170 psig for cut-in and 70 psig for the dierential.
Further adjustment may be needed. Verify the settings via refrigeration manifold gauge and perform the
nal adjustments to the readings on the gauge manifold. If your condensing unit is not equipped with a Low
Ambient Control, it features a pre-set Fan Cycling Switch.
Refrigeration Lines
A 1/4 inch O/D copper “liquid line” and a 3/8 or 1/2 inch O/D copper “suction line” connect the two units.
The refrigerant drier and the sight glass shall be installed (in that order) in the direction of the refrigerant
ow in the liquid line between the condensing unit and evaporator. Enclose the suction line in a cellular
insulation ½” wall thickness Armaex (brand name) or equal to reduce heat transfer.
Wiring System
The compressor is controlled by a “pump down cycle,” therefore, no wiring between the condensing unit
and evaporator unit is necessary. Wire the system in accordance with local codes and the enclosed wiring
diagrams (pg 22). The evaporator unit requires a standard 20 amp circuit, non-GFI. A dedicated circuit is not
mandatory, but recommended.
Charging the System (by Certied HVAC technician)
After all the piping is complete:
Open both of the service valves on the condensing unit (the unit is pressurized with nitrogen, and there
should be an audible sound of gas escaping through the service ports).
With electrical power connected to the evaporator unit, energize the solenoid valve (pressurize with dry
nitrogen) to 200psi. Leak test all ttings. The system must hold 200psi for 30 minutes.
If no leaks are found, leave the solenoid valve energized and evacuate the system through both the liquid
and suction service ports. Using a high vacuum pump, evacuate to 200 microns, measuring the vacuum
with a digital micron gauge. When evacuation is complete, break vacuum and pressurize with liquid R-134A
refrigerant.
With the electrical power turned on to the condensing unit, and the evaporator unit running, slowly feed
liquid refrigerant (R134A) into the suction service port. As the suction pressure rises to 15 PSIG, the condens-
ing unit will start. Slowly feed refrigerant while maintaining a pressure above 10 PSIG to prevent the com-
pressor from short cycling. Slowly feed refrigerant with the compressor running until the sight glass is clear
of all bubbles. Do not exceed 3.5 lbs of refrigerant. Check superheat at the evaporator outlet. Superheat
should be at 10°-12°. Check the compressor crankcase temperature after 30 minute run time – it should be
hot (115°to 140°). If it is cooler, superheat is too low. Adjust TXV to recommended superheat.
Allow the system to operate for one hour and then check the refrigerant level in the sight glass again. Ad-
ditional refrigerant may be required as the temperature of the enclosure is lowered to approximately 55°F or
the ambient temperature at the condensing unit rises above the temperature at which the unit was initially
charged. Depending on temperature, the “high side” should be approximately 175 lbs, and the ”low side” 28
lbs or more to keep the evaporator from icing. It is recommended while charging to use a digital refrigerant
scale for better accuracy in measuring the amount of charge.
SPLIT SYSTEM INSTALLATION (cont’d)