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unusualatthispointandcanbecausedbyashingfromliquidlinepressuredrop,lowsub-cooling

or low charge. It is likely that more refrigerant will be required to complete the charging procedure.

Adjusttherefrigerantchargeuntilthesub-coolingisbetween8-10°F.Theremaybeashingand/or

bubbles in the sight glass when the system is properly charged.

The system should be allowed to stabilize for 15 to 20 minutes before meaningful measurements

can be taken. After the system is allowed to stabilize, verication of a few key measurements

should be noted. The discharge pressure with R-410A should be between 340 -415 PSIG and the

sub-cooling should be between 8-10°F depending on ambient conditions. Units with R-407C the

discharge pressure should be between 240-295 PSIG. Suction pressure should be 104 PSIG or

greater with R-410A and 52 PSIG or greater with R-407C. Measure the superheat at the compres-

sor suction line at least 6 inches away from the compressor. The superheat should be between

8-15°F.

Note: Charging to a full liquid line sight glass should never be the sole means of deter-

mining the correct refrigerant charge. Other parameters such as superheat, suction pres-

sure, head pressure, sub-cooling and ambient temperature are also important. A system

charged to a clear sight glass is often overcharged.

4.2.2 Flooded System Charging

Flooded type systems are supplied with optional liquid receiver and head pressure control valve.

When the ambient temperature falls during cold weather, the head pressure control valve will regu-

latetheowofrefrigeranttoensurenearlyconstantreceiverpressure.Thecondenserispartially

oodedwithliquidrefrigerantincoldweather.Inwarmweathertheextrarefrigerantisstoredinthe

receiver.

Flooded systems require more refrigerant than fan speed control systems. Connect the pressure

gauge manifold set to the high and low ports near the compressor. Connect the charging line to the

refrigerant tank and set for liquid feed. Open the refrigerant tank valve and purge the line. Open

thehighsidevalveonthemanifoldonlyandallowtherefrigeranttoowuntilthesystempressure

equalizes. At this point the system will have 75-85% of the total refrigerant charge. Start the evapo-

rator motor. Start the compressor and check the operating pressures and temperatures.

A quick and easy way to run the compressor is using the manual switch on the unit’s microproces-

sor. Switch the compressor manual switch to the ON position. All automatic control is disabled but

safety switches will remain functional.

Before starting a compressor, the crankcase heater should be energized for a minimum

of 12 hours to reduce the possibility of liquid slugging on start-up. Failure to energize the

crankcase heater could result in compressor damage.

Using the manual switch operation will not bring the fans to full speed. Enabling the BLOWER

manual mode switch engages the contactors powering the high voltage to the plug fans but sets the

control signal to 0V.

Enabling any other manual mode switch will likewise disable all control outputs from the dap4 panel

resulting in full manual mode operation and setting the plug fans to 0V.

Data Aire gForce GT series User Manual

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