Carrier 38BYW, Installation And Start-Up Instructions Manual

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Step 13—Start-Up and Check Charge
To prevent compressor damage or personal injury, observe
the following:
• Do not overcharge system with refrigerant.
• Do not operate unit in a vacuum or at negative pressure.
• Do not disable low-pressure switch
In scroll compressor applications:
• Dome temperatures may be hot.
• In 3 phase application, incorrect phasing will cause reverse
rotation, resulting in elevated noise levels, equalized pres-
sures, and reduced current draw. Correct by reversing power
connection L1 and L2 on contactor.
To prevent personal injury wear safety glasses, protective
clothing, and gloves when handling refrigerant and observe
the following:
• Back seating service valves are not equipped with Schrader
valves. Fully back seat (counter clockwise) valve stem before
removing gage port cap.
• Front seating service valves are equipped with Schrader
valves.
Do not vent refrigerant to atmosphere. Recover during system
repair or final unit disposal.
Follow these steps to properly charge a system.
1. Fully back seat (open) liquid and vapor tube service valves.
2. Unit is shipped with valve stem(s) front seated (closed) and
caps installed. Replace stem caps after system is opened to
refrigerant flow. Replace caps finger-tight and tighten with
wrench an additional 1/6 turn for front seating valves (female
hex stem) or 1/12 turn for back seating valves (male square
stem).
3. Close electrical disconnects to energize system.
4. Set room thermostat at desired temperature.
5. Set room thermostat to HEAT or COOL and fan to ON or
AUTO mode, as desired. Operate unit for 15 minutes. Check
system refrigerant charge.
6. Factory charge is shown on outdoor unit rating plate. Adjust
charge in cooling mode by following procedure shown on the
charging table. Check charge in heating mode by following
procedure shown on heating check chart. Both are located on
outdoor unit.
SEQUENCE OF OPERATION
NOTE: Defrost control board may be equipped with 5-minute
lockout timer which may be initiated upon any interruption of
power.
With power supplied to indoor and outdoor units, transformer is
energized.
Cooling
On a call for cooling, thermostat makes circuits R-O, R-Y, and
R-G. Circuit R-O energizes reversing valve, switching it to cooling
position. Circuit R-Y energizes contactor, starting outdoor fan
motor and compressor circuit. R-G energizes indoor unit blower
relay, starting the indoor blower motor on high speed.
When the thermostat is satisfied, its contacts open, de-energizing
the contactor and blower relay. Compressor and motors should
stop.
NOTE: If indoor unit is equipped with a time-delay relay circuit,
the blower will run an additional 90 sec to increase system
efficiency.
Heating
On a call for heating, thermostat makes circuits R-Y and R-G.
Circuit R-Y energizes contactor, starting outdoor fan motor and
compressor. Circuit R-G energizes indoor blower relay, starting
blower motor on high speed.
Should temperature continue to fall, R-W2 is made through
second-stage room thermostat bulb. Circuit R-W2 energizes a
sequencer, bringing on first bank of supplemental electric heat and
providing electrical potential to second heater sequencer (if used).
If outdoor temperature falls below setting of outdoor thermostat
(field-installed option), contacts close to complete circuit and bring
on second bank of supplemental electric heat.
When thermostat is satisfied, its contacts open, de-energizing the
contactor and sequencer. All heaters and motors should stop.
Defrost
The defrost control is a time/temperature control which includes a
field-selectable (quick-connects located at board edge) time period
between defrost cycles (30, 50, and 90 minutes), factory set at 90
minutes.
The electronic timer and defrost cycle start only when contactor is
energized and defrost thermostat is closed.
The defrost mode is identical to cooling mode except that outdoor
fan motor stops and second-stage heat is turned on to continue
warming conditioned space.
CARE AND MAINTENANCE
For continuing high performance and to minimize possible equip-
ment failure, it is essential that periodic maintenance must be
performed on this equipment.
Leave User’s Manual with homeowner. Explain system operation
and periodic maintenance requirements outlined in manual. Fre-
quency of maintenance may vary depending upon geographic
areas, such as coastal applications which require more frequent
maintenance.
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