40 McQuay IM 937
System Check, Test, and Start
System Check, Test, and Start
General
Start-up and service of this equipment must be performed only
by trained, experienced personnel. A representative of the
owner or the operator should be present during start-up to
receive instruction in unit operation, care, and adjustment.
Complete a check, test, and start-up procedure. The completed
check test and start form (supplied with each unit) must be
signed and returned to McQuay International.
Note: Before opening service panels, always lock out and tag
out the power disconnect switch.
Pre Start-Up
1 Check that the unit is completely and properly installed
with ductwork connected.
2 Check that all construction debris is removed and filters are
clean.
3 With all electrical disconnects open, check all electrical
connections to be sure they are tight. Although all factory
connections are tight before shipment, shipping vibration
can cause loosening.
4 Check all compressor valve connections for tightness to
avoid refrigerant loss at start-up. Although all factory
connections are tight before shipment, shipping vibration
can cause loosening. See Table 13 for proper valve torque
values.
5 Check the tightness of setscrews in bearings, drives, and
fan wheels. If retightening is needed, make certain fan
wheels are centered between the inlet openings and
setscrews are torqued per Table 14.
6 Check that the fan rotates freely. Check belt tension and
alignment.
7 Check that the unit condenser water connections and
condensate drain connections were made.
8 Before attempting to operate the unit, review the control
layout description to become familiar with the control
locations.
9 Review all equipment service literature and the unit wiring
diagrams supplied with each unit.
10 Review optional controls to determine which are included
in the unit.
11 Check that the return air temperature sensor (and optional
room sensor) is installed in the return air duct and that the
wiring terminations were made at the unit input board.
12 Check that entering and leaving condenser water
temperature sensors are mounted.
13 Check that the optional duct static pressure sensor is
connected to the duct with appropriate tubing. The unit may
have one optional static pressure sensor, SPS1. The other
option would be SPS1 and SPS2.
14 Check the voltage of the unit power supply and see that it is
within the allowed ±10% tolerance. Phase voltage
unbalance must be within ±2%.
15 Check the unit power supply wiring for adequate ampacity
and a minimum insulation rating of 75°C.
16 Verify that all mechanical and electrical inspections were
completed per local codes.
17 Open all liquid line service valves and tighten all packing
nuts
18 Open the compressor suction and discharge shutoff valves
until backseated. Always replace valve seal caps.
19 For units with compressor crankcase heaters: Make sure the
unit switch S1 is in the OFF position. Then throw the main
power disconnect to ON. This energizes the crankcase
heaters. Wait a minimum of 24 hours before starting the
unit.
WARNING
ELECTRIC SHOCK HAZARD
The equipment frame must be bonded to the building electrical
ground with the grounding terminal provided or other
acceptable means. Failure to properly ground can result in
electric shock, equipment damage, severe personal injury, or
death. Lock out and tag out all power sources to equipment
before servicing.
WARNING
Always open the power disconnect switch before opening
service panels. Failure to do so can result in electric shock,
equipment damage, severe personal injury, or death.
Table 13: Valve Torques
Coupling nut
size (in)
Gage port cap
torque (lbs-ft)
Stem cap torque
(lbs-ft)
Coupling nut
torque (lbs-ft)
1.00 7±1 32±2 55+5
1.25 7±1 32±2 90+10
1.75 7±1 45±3 205+15
Table 14: Setscrew Torque
Setscrew diameter Torque min. (ft.-lbs.)
#10 4.3
1/4” 10.0
5/16” 20.0
3/8” 25.0
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