4.The belt drive blower contactor closes its contacts L1, L2 and L3 to T1, T2 and T3 to provide power to the supply fan motor.
5.Check supply fan rotation. If the supply fan is rotating in the wrong direction, disconnect and lock off Single Point Power Block. Do not attempt to change load side wiring. Internal wiring is set at the factory to assure that the supply fan and compressors all rotate in the proper direction. Verification of correct supply fan rotation at initial startup will also indicate correct compressor rotation. Reconnect power and check for proper operation.
6.Compressor contactor closes its contacts L1, L2 and L3 to T1, T2 and T3 to provide power to the compressor motor COMP 1; COMP 2, if conditions are correct. In addition, contactor C1 closes its contact L3 to T3 , energizing the condenser fan motor.
WARNING
BURN HAZARD!
DO NOT TOUCH! DISCHARGE LINE MAY BE HOT!
7.Check that each compressor is operating correctly. The scroll compressors in these units MUST operate in the proper rotation. To ensure the compressors are operating in the correct direction, check the compressor discharge line pressure or temperature after each compressor is started.
The discharge pressure and discharge line temperature should increase. If this does not occur and the compressor is producing an exceptional amount of noise, perform the following checks.
•Ensure all compressors and the supply fan motor are operating in the proper direction. If a single motor is operating backwards, check the power wiring for that motor and correct any leads that have been interchanged at the contactor or at the motor.
•If all of the motors are operating backward, disconnect the unit power supply and lock it in the “OFF” position. Switch two leads of the power supply at the unit Single Point Power Block. Reconnect power and check for compressor and supply fan motor operation.
8.With all safety devices closed, the system will continue cooling operation until the thermostat is satisfied.
9.Disconnecting the jumper wire between R and Y1 and Y2 and between R and G on TB1 terminal block will simulate a satisfied thermostat. The compressors will cycle off and IIC (pin 12) will initiate its time delay cycle. The compressor and the supply fan will cycle off.
10.After a time delay of approximately 3 minutes, the compressor control circuits will be ready to respond to a subsequent call for cooling from the wall thermostat.
11.Open disconnect switch. Reconnect the field thermostat wire at terminal R on terminal block TB1.
REFRIGERATION PERFORMANCE CHECK
Under normal summertime (full load) operating conditions, superheat should be between 8°F and 12°F and
GAS SUPPLY PRESSURES & REGULATOR ADJUSTMENTS
WARNING
SHOULD OVERHEATING OCCUR OR THE GAS SUPPLY FAIL TO SHUT OFF, TURN OFF THE MANUAL GAS SHUTOFF VALVE EXTERNAL TO THE UNIT BEFORE TURNING OFF THE ELECTRICAL SUPPLY.
WARNING
TO AVOID PROPERTY DAMAGE, PERSONAL INJURY OR DEATH, DO NOT FIRE GAS UNIT WITH FLUE BOX COVER REMOVED.
NOTE: Except during brief periods when gas pressures are being measured by qualified service personnel, the furnace access panel must always be secured in place when the furnace is in operation. An inspection port in the access panel is provided to monitor the flame.
The first step in checking out the
The supply gas pressure should be adjusted to 7.0" w.c. on natural gas and 11.0" on LP gas with the gas burners operat- ing. If there is more than one unit on a common gas line, the pressures should be checked with all units under full fire. A supply pressure tap is provided on the upstream side of the gas valve. A manifold pressure tap is provided on the mani- fold. The normal manifold pressure for full input is 3.5" w.c. on natural gas and 10.0" w.c. for propane gas. Minimum gas supply pressure is 5.5" w.c. for natural gas and 11.0" for pro- pane gas. In order to obtain rating, gas supply pressure must be 11.0" w.c. for propane gas.
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