Carrier WeatherMaker 50KCQ A04 Series Service And Maintenance Instructions page 56

RETURN-AIR FILTERS
Ensure the correct filters are installed in the unit (see
Appendix B - Physical Data on page 59). Do not operate unit
without return-air filters in place.
OUTDOOR-AIR INLET SCREENS
Outdoor-air inlet screen must be in place before operating unit.
COMPRESSOR MOUNTING
Compressors are internally spring-mounted. Do not loosen or
remove compressor hold down bolts.
INTERNAL WIRING
Check all electrical connections in unit control boxes. Tighten
as required.
COMPRESSOR ROTATION
CAUTION
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution can result in premature wear
and damage to equipment.
Scroll compressors can only compress refrigerant if rotat-
ing in the right direction. Reverse rotation for extended
times can result in internal damage to the compressor.
Scroll compressors are sealed units and cannot be repaired
on site location.
On 3-phase units with scroll compressors, it is important to be cer-
tain 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 pressure
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 pressure
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 and apply lockout/tag-out
procedures.
3. Reverse any two of the unit power leads.
4. Re-energize to the compressor. Check pressures.
The suction and discharge pressure levels should now move to
their normal start-up levels.
NOTE: When the compressor is rotating in the wrong direction,
the unit will make an elevated level of noise and will not provide
cooling.
REFRIGERANT SERVICE PORTS
Each unit system has two
service ports: one on the suction line, and one on the compres-
sor discharge line. Be sure that caps on the ports are tight.
COOLING
Set space thermostat to OFF position. To start unit, turn on
main power supply. Set system selector switch at COOL posi-
tion and fan switch to AUTO. position. Adjust thermostat to a
setting below room temperature. Compressor starts on closure
of contactor.
Check unit charge. Refer to Refrigerant Charge section on
page 14.
Reset thermostat at a position above room temperature. Com-
pressor will shut off. Evaporator fan will shut off after a 60-
second delay if the dip switch for the indoor fan off delay on
the Defrost Control Board (DFB) is set to on.
To shut off unit
Set system selector switch to the OFF position. Resetting ther-
mostat at a position above room temperature shuts the unit off
temporarily until space temperature exceeds thermostat setting.
HEATING
To start unit, turn on main power supply.
Set system selector switch to the HEAT position and set ther-
mostat at a setting above room temperature. Set fan to AUTO
position.
First stage of thermostat energizes compressor heating. Second
stage of thermostat energizes electric heaters (if installed).
Check heating effects at air supply grille(s).
If electric heaters do not energize, reset limit switch (located on
supply-fan scroll) by pressing button located between termi-
nals on the switch.
To shut off unit
Set system selector switch to the OFF position. Resetting ther-
mostat at a position below room temperature temporarily shuts
unit off until space temperature falls below thermostat setting.
VENTILATION (CONTINUOUS FAN)
Set fan and system selector switches at ON and OFF positions,
respectively. Supply fan operates continuously to provide con-
stant air circulation.
56
1 / -in. SAE flare (with check valves)
4