Unit installation

14 ACZ 010A through 039A IOMM ACZ1-2
Start-up and Shutdown
Pre Start-up
1. The chilled-water system should be flushed and cleaned or air filters checked for
cleanliness on DX systems.
2. Open all electric disconnects and check all electric connections for tightness.
3. Inspect all water piping for flow direction and correct connections at the evaporator or
ductwork for tightness and completeness.
4. Verify that thermostat connections for two stages of control have been connected to unit
terminals 23 / J5-ID7 and 28 / J5- ID-8.
5. Check compressor oil level. The oil level should be visible in the oil sightglass.
6. Check voltage of the unit power supply and make certain voltage is within ±10% of
nameplate rating. Check unit power supply wiring for proper ampacity and a minimum
insulation temperature of 75°C. Check for proper phasing using a phase sequence
meter.
7. Verify all mechanical and electrical inspections have been completed according to local
codes.
8. Open control stop switch S1(off). Turn on the main power and control disconnect
switches. This will energize crankcase heaters. Wait at least 24 hours before starting
up unit.
Start-up
1. Start auxiliary equipment by turning on the following: time clock (if present), ambient thermostat
and/or remote on/off switch, chilled water pump or air handler.
2. If the field supplied staging control calls for cooling, the unit will begin the start-up
sequence.
3. After running the unit for a short time, check the oil level in the compressor (1/4 to 1/3 of the
glass), rotation of fans, and flashing in refrigerant sight glass.
4. Verify superheat temperature is at the factory setting of 8 to 12 degrees F (4.4 to 6.7
degrees C).
5. After system performance has stabilized, complete the current ACZ Start-Up Form
(obtainable from the local McQuay sales office) to establish inception of warranty
benefits. Return the form to McQuay International through your sales representative.
Sequence of Operation
The following sequence of operation is typical for Models ACZ 010A through ACZ 039A.
It can vary depending upon options.
Start-Up
With the control circuit power on, 115V power is applied through the control circuit fuse F1
to the compressor crankcase heaters, the compressor motor protections and the primary of
the 24V control circuit transformer. The 24V transformer provides power to the
microprocessor controller.
If an optional remote time clock or remote manual switch is field wired to the unit
(terminals 25 and 35), it must be closed in order to start the unit. The operation of the unit
is then under the control of the field supplied staging thermostat. A water or air flow switch
is recommended across terminals 26 and 36 to prove flow before starting compressors. If
not used, a jumper is required across the terminals. The two compressors will start when
the normally open staging contacts close.