START-UP
CRANKCASE HEATER
The crankcase heaters must be energized at least 8 hours bef- ore starting the compressor. To energize the crankcase heat- ers, the main disconnect switch must be closed. During this 8 hour period, the system switch on the room thermostat must be “OFF” to prevent the compressor from starting.
CAUTION: DO NOT ATTEMPT TO START THE COMPRES- SOR WITHOUT AT LEAST 8 HOURS OF CRANK- CASE HEAT OR COMPRESSOR DAMAGE WILL OCCUR.
Make sure that the bottom of the compressor is warm to the touch to prove crankcase heater operation.
PRE-START CHECK
Before starting the unit, complete the following check list:
1.Have sufficient clearances been provided?
2.Has all foreign matter been removed from the interior of the unit (tools, construction or shipping materials, etc.)?
3.Have the condenser fans been rotated manually to check for free rotation?
4.Are all wiring connections tight?
5.Does the available power supply agree with the nameplate data on the unit?
6.Is the control circuit transformer set for the proper voltage?
7.Have the fuses, disconnect switch and power wire been sized properly?
8.Are all compressor
9.Are any refrigerant lines touching each other or any sheet metal surface? Rubbing due to vibration could cause a re- frigerant leak.
10.Are there any visible signs of a refrigerant leak, such as oil residue?
11.Is any electrical wire laying against a hot refrigerant line?
INITIAL START-UP
1.Supply power to the unit through the disconnect switch at least 8 hours prior to starting the compressor.
2.Move the system switch on the thermostat to the AUTO or COOL position.
3.Reduce the setting of the room thermostat to energize the compressor.
4.Check the operation of the evaporator unit per the manufac- turer's recommendations.
5.With an ammeter, check the compressor amps against the unit data plate.
6.Check for refrigerant leaks.
7.Check for any abnormal noises and/or vibrations, and make the necessary adjustments to correct (e.g. fan blade(s) touching shroud, refrigerant lines hitting on sheet metal, etc.)
8.After the unit has been operating for several minutes, shut off the main power supply at the disconnect switch and inspect all factory wiring connections and bolted surfaces for tight- ness.
CAUTION: DO NOT ATTEMPT TO START THE COMPRES- SOR WITHOUT AT LEAST 8 HOURS OF CRANK- CASE HEAT OR COMPRESSOR DAMAGE WILL OCCUR.
SECURE OWNER'S APPROVAL: When the system is functioning properly, secure the owner's approval. Show him the location of all disconnect switches and the thermostat. Teach him how to start and stop the unit and how to adjust temperature settings within the limitations of the system.
OPERATION
UNIT OPERATION - 7-1/2, 10 & 12-1/2 TON
When the external control calls for cooling at terminal Y1:
1.The system controller (SC) is energized. The system con- troller starts the compressors and enables the condenser fans by energizing contactor 1M (and 2M on the
The single condenser fan is energized with the compressor on the
Condenser fan motor #1 is energized with the compressors on the 10 and
2.Safety Lockout: The system controller (SC) has a lockout circuit to prevent compressor
SC provides a 90 second bypass of the low pressure switch LP to prevent nuisance lockouts during unit
A malfunction light (24V, 2 A max. resistive load) can be en- ergized through SC, by connecting the light between termi- nals X and B on TB1. Terminal X will energize when SC locks out.
3.Unit is equipped with an
NOTE: To reset the unit after a lockout:
A. Turn the system switch on the thermostat to the “OFF” position and back to the “COOL” position.
OR
B.Increase the set point of the room thermostat above the temperature in the conditioned space and return it to its original setting.
14 | Unitary Products Group |
