Step 15 Check Charge - Carrier 25HNA Infinity
Series Installation Instructions Manual

Defrost Hold
On 25HNA6 models, in a non−communicating system, if the
thermostat becomes satisfied (Y1 or Y1 and Y2) before the
defrost cycle is terminated, the control will "hold" in defrost
mode and finish the defrost cycle on the next call for heat.
On 25HNA6 models, with communicating Infinity Control and
all 25HNA9 models, defrost hold is not needed in a
communicating system because the User Interface will complete
the defrost cycle before shutting down the system.
Forced Defrost
On 25HNA6 models with non−communicating (non−Infinity)
control, forced defrost can be initiated by manually shorting the
2−pin header labeled FORCED DEFROST (see Fig 9) on the
control board for 5 seconds then releasing.
On 25HNA6 and 25HNA9 with communicating (Infinity)
control, forced defrost is initiated with the User Interface.
On all models, during a Forced Defrost:
S
If coil temperature is at defrost temperature of 32_F,
and outdoor air temperature is below 50_F, a full
defrost sequence will occur.
S
If coil temperature or outdoor air temperature does not
meet the above requirements, an abbreviated 30 second
defrost will occur.
Quiet Shift
Quiet Shift is a field−selectable defrost mode which may
eliminate occasional noise that could be heard at the start of the
defrost cycle and restarting of the heating cycle. On 25HNA6
models with non−communicating system, this feature must be
enabled by selecting the 3rd position of the 3−position dip switch.
For 25HNA6 and 25HNA9 models with communicating
(Infinity) systems, it must be enabled at the User Interface. When
activated, the following sequence of operation will occur.
Reversing valve will energize and compressor will turn off for 30
seconds, then turn back on to complete defrost. At the end of the
defrost cycle, the reversing valve de−energizes, compressor will
turn off for another 30 seconds, and the fan will turn off for 40
seconds, before starting in the heating mode.
Liquid−Line Solenoid Accessory
In heat pump long−line applications, a liquid−line solenoid is
required to control refrigerant migration in the heating mode. The
solenoid should be installed near the outdoor unit with the arrow
facing the outdoor unit. This is the direction of flow control. See
application manual for long−line application details.
Accessory Liquid Solenoid with Infinity Communicating
Control:
When using the Infinity Control, the liquid−line
solenoid output is provided at the Y1 connection. Connect the
solenoid as shown in the wiring label diagram. This is a 24vac
output that is energized whenever the compressor is energized. It
closes, in the compressor off mode, to prevent refrigerant
migration into the unit through the liquid−line.
On 25HNA6 Models with Accessory Liquid Solenoid Using a
Non−Communicating Thermostat:
connect to the Y1 and C terminal connections. The liquid
solenoid closes, in the compressor off mode, to prevent
refrigerant migration into the unit through the liquid−line.
The liquid solenoid is
Step 15 Check Charge
Unit Charge
Factory charge and charging method are shown on unit
information plate. Charge Puron refrigerant units with cylinder in
inverted position and a commercial−type metering device in
manifold hose. Charge refrigerant into suction line.
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. Favorable conditions fall within the ranges given on
the charging chart on the outdoor unit plate.
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
This system requires charging by the subcooling method.
1. On all units, operate unit a minimum of 10 minutes in
high−stage before checking charge.
On 25HNA6 models, charging in low stage may cause
compressor chattering and possible damage to the
compressor.
2. Measure liquid service valve pressure by attaching an
accurate gauge 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 unit rating plate for required subcooling
temperature. Subcooling amount is for high stage
operation.
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.
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