Start-Up; Unit Preparation; Return-Air Filters; Compressor Mounting - Payne PA1R Series Installation, Start-Up And Service Instructions Manual

START-UP

I. UNIT PREPARATION
Make sure that unit has been installed in accordance with
installation instructions and applicable codes.
II. RETURN-AIR FILTERS
Make sure correct filters are installed in unit (see Table 1).
Do not operate unit without return-air filters.
III. COMPRESSOR MOUNTING
Compressors are internally spring mounted. Do not loosen or
remove compressor holddown bolts.
IV. INTERNAL WIRING
Check all electrical connections in unit control boxes; tighten
as required.
V. REFRIGERANT SERVICE PORTS
To service refrigerant service ports, remove refrigerant serv-
ice port access panel. See Fig. 8. Each unit system has
4 Schrader-type service ports: one on the suction line, one on
the liquid line, and two on the compressor discharge line. Be
sure that caps on the ports are tight. When a controls up-
grade package is used, one Schrader-type valve is located
under both the high-pressure switch and the low-pressure
switch.
VI. COMPRESSOR ROTATION
On PA1R072 scroll compressor units, it is important to be
certain compressor is rotating in the proper direction. To
determine whether or not compressor is rotating in the proper
direction:
1. Connect service gages to suction and discharge pres-
sure fittings.
2. Energize the compressor.
3. The suction pressure should drop and the discharge pres-
sure should rise, as is normal on any start-up.
If the suction pressure does not drop and the discharge pres-
sure does not rise to normal levels:
1. Note that the evaporator fan is probably also rotating
in the wrong direction.
2. Turn off power to the unit.
3. Reverse any two of the unit power leads.
4. Reapply power to the compressor.
The suction and discharge pressure levels should now move
to their normal start-up levels.
NOTE: When the compressor is rotating in the wrong direc-
tion, the unit makes an elevated level of noise and does not
provide cooling.
VII. COOLING
Set space thermostat to OFF position. Set system selector switch
at COOL position and fan switch at AUTO. position. Adjust
thermostat to a setting below room temperature. Compres-
sor starts on closure of contactor.
Check cooling effects at a setting below room temperature.
Check unit charge. Refer to Refrigerant Charge Section,
page 27.
Reset thermostat at a position above room temperature. Com-
pressor will shut off.
To Shut Off Unit
Set system selector switch at OFF position. Resetting ther-
mostat at a position above room temperature shuts unit
off temporarily until space temperature exceeds thermostat
setting.
VIII. SAFETY RELIEF
A soft solder joint in the suction line at the low-pressure serv-
ice port provides pressure relief under abnormal tempera-
ture and pressure conditions.
IX. VENTILATION (Continuous Fan)
Set fan and system selector switches at ON and OFF posi-
tions, respectively. Evaporator fan operates continuously to
provide constant air circulation.
X. OPERATING SEQUENCE
A. Cooling, Units with Durablade Economizer
When the outdoor-air temperature is above the outdoor-air
thermostat (OAT) setting and the room thermostat calls for
cooling, compressor contactor is energized to start compres-
sor and the outdoor (condenser) fan motor (OFM). The indoor
(evaporator) fan motor (IFM) is energized and the econo-
mizer damper moves to the minimum position. After the ther-
mostat is satisfied, there is a 30-second delay before the
evaporator fan turns off. The damper then moves to the fully
closed position. When using continuous fan, the damper moves
to the minimum position.
When the outdoor-air temperature is below the OAT setting
and the thermostat calls for cooling, the economizer damper
moves to the minimum position. If the supply-air tempera-
ture is above 57 F, the damper continues to open until it reaches
the fully open position or until the supply-air temperature
drops below 52 F.
When the supply-air temperature falls between 57 F and
52 F, the damper will remain at an intermediate open posi-
tion. If the supply-air temperature falls below 52 F, the damper
will modulate closed until it reaches the minimum position
or until the supply-air temperature is above 52 F. When the
thermostat is satisfied, the damper moves to the fully closed
position when using AUTO. fan or to the minimum position
when using continuous fan.
If the outdoor air alone cannot satisfy the cooling require-
ments of the conditioned space, economizer cooling is inte-
grated with mechanical cooling, providing two stages of
cooling. Compressor and the condenser fan will be energized
and the position of the economizer damper will be deter-
mined by the supply-air temperature. When the second stage
of cooling is satisfied, the compressor and OFM will be deen-
ergized. The damper position will be determined by the supply-
air temperature. When the first stage of cooling is satisfied,
there is a 30-second delay before the evaporator fan shuts
off. The damper then moves to the fully closed position. When
using a continuous fan, the damper moves to the minimum
position.
B. Accessory Heating, Units with Economizer
Upon a call for heat through W1, the IFC energizes to start
the evaporator fan and the economizer damper blade opens
to the minimum position. If the two-position damper is used,
the outdoor-air damper opens to the minimum position when-
ever the evaporator fan runs.
When W1 is deenergized, the evaporator-fan motor stops,
and economizer/two-position damper moves to the closed
position.
—24—