Carrier 38TDB instruction manual Required Liquid-Line Temperature F, Check Charge

Step 11—Check Charge

Service valve gage ports are not equipped with Schrader valves. To prevent personal injury, make sure gage manifold is connected to the valve gage ports before moving valves off fully back seated position. Wear safety glasses and gloves when handling refrigerant.

UNIT CHARGE

Factory charge and charging method are shown on pink charging label. With unit operating, charge Puron® units with liquid using a commercial type metering device in manifold hose. Charge refrigerant into suction line.

NOTE: Unit is to be charged in high capacity only. Charging in low capacity may cause compressor chattering and possible damage to the compressor.

NOTE: If 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.

COOLING ONLY PROCEDURE

1.Operate unit a minimum of 15 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 line near outdoor coil.

4.Refer to Table 4 for required subcooling temperature.

5.Refer to Table 3. 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.

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UNIT CHARGE

Factory charge and charging method are shown on pink charging label. Puron® refrigerant cylinders contain a dip tube which

allows liquid refrigerant to flow from cylinder in upright

position. Charge Puron units with cylinder in upright position and a commercial type metering device in manifold hose. Charge refrigerant into suction line.

NOTE: Unit is to be charged in high capacity only. Charging in low capacity may cause compressor chattering and possible damage to the compressor.

NOTE: If 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.

Step 12—System Functions and Sequence of Operation

The outdoor unit control system has special functions. The following is an overview of the two-speed control functions:

COOLING OPERATION

This product utilizes a 2-stage cooling indoor thermostat. With a call for first stage cooling (Yl), the outdoor fan and low capacity compressor are energized. If low capacity cannot satisfy cooling demand, high capacity is energized (Yl and Y2 or Y2 only) by the second stage of indoor thermostat. After second stage is satisfied,

Table 3—Required Liquid-Line Temperature (°F)

LIQUID		REQUIRED SUBCOOLING
PRESSURE AT			TEMPERATURE
SERVICE VALVE					(°F)
(PSIG)	8	12		14		16	18	18
189	58	56		54		52	50	48
195	60	58		56		54	52404	50
202	62	60		58		56	54	52
208	64	62		60		58	56	54
215	66	64		62		60	58	56
222	68	66		64		62	60	58
229	70	68		66		64	62	60
236	72	70		68		66	64	62
243	74	72		70		68	66	64
251	76	74		72		70	68	66
259	78	76		74		72	70	68
266	80	78		76		74	72	70
274	82	80		78		76	74	72
283	84	82		80		78	76	74
291	86	84		82		80	78	76
299	88	86		84		82	80	78
308	90	88		86		84	82	80
317	92	90		88		86	84	82
326	94	92		90		88	86	84
335	96	94		92		90	88	86
345	98	96		94		92	90	88
354	100	98		96		94	92	90
364	102	100		98		96	94	92
374	104	102		100		98	96	94
384	106	104		102		100	98	96
395	108	106		104		102	100	98
406	110	108		106		104	102	100
416	112	110		108		106	104	102
427	114	112		110		108	106	104
439	116	114		112		110	108	106
450	118	116		114		112	110	108
462	120	118		116		114	112	110
474	122	120		118		116	114	112
486	124	122		120		118	116	114
499	126	124		122		120	118	116
511	128	126		124		122	120	118

the unit returns to low-speed operation until first stage is satisfied or until second stage is required again. When both first stage and second stage cooling are satisfied, the compressor will shut off.

NOTE: If unit has not operated within the past 12 hr, or following a unit power-up, upon the next thermostat high- or low-speed demand, unit operates for a minimum of 5 minutes on high-speed.

NOTE: When two-speed unit is operating at low speed, system vapor (suction) pressure will be higher than a standard single- speed system or high-speed operation.

NOTE: Outdoor fan motor will continue to operate for one minute after compressor shuts off, when outdoor ambient is greater than or equal to 100°F.

STATUS FUNCTION LIGHTS

A system control STATUS function light is located on the outdoor unit control board. (See Fig. 12.) The STATUS light provides indication signals for several system operations. See Table 5 for codes and definitions. Table 5 also provides the order of signal importance.

NOTE: Only one code will be displayed on the outdoor unit control board (the most recent, with the highest priority).

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