Carrier 38EYA instruction manual Check Charge, Unit Charge, Cooling only Procedure Example

	T2 C
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O	DFT
R	T1
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SPEEDUP	P1
	J1	P3	90 INTERVALTIMER	60 30	30 60	120
	DFT		OFF	QUIET SHIFT		ON
	Speedup				Quiet
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OF2 OF1

CESO130076–00

Defrost interval

DIP switches

A99442

Fig. 19—Defrost Control

Step 14—Check Charge

UNIT CHARGE

Factory charge is shown on unit rating plate. To check charge in cooling mode, refer to Cooling Only Procedure. To check charge in heating mode, refer to Heating Check Chart Procedure.

COOLING ONLY PROCEDURE

NOTE: If superheat or subcooling charging conditions are not favorable, charge must be weighed in accordance with unit rating plate ± 0.6 oz/ft of 3/8-in. liquid line above or below 15 ft respectively.

EXAMPLE:

To calculate additional charge required for a 25-ft line set:

25 ft - 15 ft = 10 ft X 0.6 oz/ft = 6 oz of additional charge

Units installed with cooling mode TXV require charging with the subcooling method.

1.Operate unit a minimum of 10 minutes before checking charge.

2.Measure liquid service valve pressure by attaching an accurate gage to service port.

3.Measure liquid line temperature by attaching an accurate thermistor type or electronic thermometer to liquid near outdoor coil.

4.Refer to Heat Pump Charging Instructions label on outdoor unit.

5.Refer to Table 4. Find the point where required subcooling temperature intersects measured liquid service valve pressure.

6.To obtain required subcooling temperature at a specific liquid line pressure, add refrigerant if liquid line temperature is higher than indicated or reclaim refrigerant if temperature is lower. Allow a tolerance of ± 3 °F.

HEATING CHECK CHART PROCEDURE

To check system operation during heating cycle, refer to the HEAT Pump Charging Instructions label on outdoor unit. This chart indicates whether a correct relationship exists between system operating pressure and air temperature entering indoor and outdoor units. If pressure and temperature do not match on chart, system refrigerant charge my not be correct. Do not use chart to adjust refrigerant charge.

NOTE: In heating mode, check refrigerant charge only when pressures are stable. If operating conditions cause PressureGuard switch to open and outdoor fan to cycle, check refrigerant charge in cooling or lower indoor dry bulb temperature. If in doubt, remove charge and weigh in correct refrigerant charge.

NOTE: When charging is necessary during heating season, charge must be weighed in accordance with unit rating plate ± 0.6 oz/ft of 3/8-in. liquid line above or below 15 ft respectively.

EXAMPLE:

To calculate additional charge required for a 25-ft line set:

25 ft - 15 ft = 10 ft X 0.6 oz/ft = 6 oz of additional charge

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