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Thermostat Unit Control
Power
Fig. 12 - Control Connections
A10023
PERSONAL INJURY AND ENVIRONMENTAL
HAZARD
Failure to relieve system pressure could result in personal
iniury and/or death.
Relieve pressure and recover all refrigerant before system
repair or final unit disposal.
Wear safety glasses and gloves when handling refrigerant.
Keep torches and other ignition sources away from
refrigerants and oils.
3. Make the following inspections:
a. Inspect for shipping and handling damages, such as
broken lines, loose parts, disconnected wires, etc.
b. Inspect for oil at all refrigerant tubing connections and
on unit base. Detecting oil generally indicates a
refrigerant leak. Leak test all refrigerant tubing
connections using electronic leak detector, or
liquid-soap solution. If a refrigerant leak is detected, see
following Check for Refrigerant Leaks section.
c. Inspect all field- and factory-wiring connections. Be
sure that connections are completed and tight.
d. Ensure wires do not touch refrigerant tubing or sharp
sheet metal edges.
e. Inspect coil fins. If damaged during shipping and
handling, carefully straighten fins with a fin comb.
4. Verify the following conditions:
a. See Outdoor Fan Adjustment section.
b. Make sure that air filter is in place.
c. Make sure that condensate drain pan and trap are filled
with water to ensure proper drainage.
d. Make sure that all tools and miscellaneous loose parts
have been removed.
START-UP
Step 1 -- Check for Refrigerant Leaks
Proceed as follows to locate and repair a refrigerant leak and to
charge the unit:
1. Locate leak and make sure that refrigerant system pressure
has been relieved and reclaimed from both high- and
low-pressure ports.
2. Repair leak following accepted practices.
NOTE: Install a filter drier whenever the system has been opened
for repair.
3. Add a small charge of Puron (R-410A) refrigerant vapor to
system and leak-test unit.
4. Recover refrigerant from system and evacuate to 500
microns if no additional leaks are found.
5. Charge unit with Puron (R-410A) refrigerant, using an
accurate scale. Refer to unit rating plate for required charge.
Step 2 -- Start-Up Cooling and Make Adjust-
ments
Complete the required procedures given in the Pre-Start-Up
section before starting the unit. Do not jumper any safety devices
when operating the unit. Do not operate the unit in cooling mode
when the outdoor temperature is below 40°F (4.4°C) (unless
accessory low-ambient kit is installed). Do not rapid cycle the
compressor. Allow 5 min. between "on" cycles to prevent
compressor damage.
CHECKING COOLING AND HEATING CONTROL
OPERATION
Start and check the unit for proper cooling control operation as
follows:
1. Place room thermostat SYSTEM switch in OFF position.
Observe that blower motor starts when FAN switch is
placed in ON position and shuts down within 60 sec. when
FAN switch is placed in AUTO position.
2. Place SYSTEM switch in COOL position and FAN switch
in AUTO position. Set control below room temperature.
Observe that compressor, outdoor fan, and indoor blower
motors start. Observe that cooling cycle shuts down when
control setting is satisfied.
3. If unit is equipped with electric heat, place system switch in
HEAT position. Observe that indoor fan energizes. Set
control above room temperature. Observe that heating cycle
shuts down when control setting is satisfied.
4. When using an automatic changeover room thermostat,
place both SYSTEM and FAN switches in AUTO positions.
Observe that unit operates in Cooling mode when
temperature control is set to call for Cooling (below room
temperature), and unit operates in Heating mode when
temperature control is set to call for Heating, if equipped
with electric heat (above room temperature).
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