Manual 7960-848B
Page
2 of 12
Installation
1. Disconnect all power to the unit. Remove control
panel inner and outer covers, upper front panel and
right-side condenser inlet grille.
2. Mount supplied 8607-017 terminal block into
control panel with supplied 1012-066 screw as
shown in Figure 1 or Figure 2 (page 4). Terminal
block comes installed in W12 unit; see Figure 3 on
page 5.
3. Disconnect black high voltage outdoor motor
lead from compressor contactor and reconnect
to terminal block that was installed in Step 1 as
shown in Figure 1.
4. Remove the service port cap from the liquid line.
Install the low ambient control (LAC) on the liquid
line by screwing it into the service port. Snug the
connection with wrenches and check for leaks.
See Figure 4 (page 6), Figure 5 (page 7) or Figure
6 (page 8). Route low ambient control wires up
through the bushing in the bottom of the control
panel. Route the wires through the cable duct in
the control panel as shown in Figure 1 or Figure 2.
5. Install outdoor temperature switch assembly to
the fan shroud and route the wires to the control
panel as shown in Figure 4, Figure 5 and Figure 6.
This switch defeats Balanced Climate airflow when
the temperature falls below 50°F to help prevent
evaporator freeze up. Refer to the unit installation
manual for more information on Balanced Climate
operation.
6. Install freeze protect thermostat to the evaporator
coil as shown in Figure 7 (page 9), Figure 8 (page
10) and Figure 9 (page 11). For W12, W30 or W36
units, route the wires down through the copper
bushing and into the control panel with the blower
motor wires. For W42, W48, W60,W72 and W*SAC
units, route the wires down through the bushings in
the blower partition and filter partition beside the
filters and into the control panel.
7. Connect the low ambient control wires to the
terminal block and T2 of the compressor contactor
(see Figure 1, Figure 2 or Figure 3).
8. Find the purple wire not connected to anything
that is tucked in the cable duct (see Figures 1 or
2). Pull it out and connect it to the LAC terminal
block on the terminal that is separate from the
LAC control wire (the purple wire in W12 units
comes connected to the terminal block—see Figure
3). Connect the end of the outdoor temperature
switch that has the insulated quick connect to the
terminal block beside the purple wire. Connect the
other end of the outdoor temperature switch to the
Y terminal on the compressor control module for
1-phase units or on the phase monitor for 3-phase
units. Refer to Figure 10 on page 12 or the unit
wiring diagram.
9. Connect the freeze protect thermostat wires in line
with the “Y” input signal to the compressor control
module (CCM). Refer to the unit wiring diagram.
For 1-phase units, connect the end with the 1/4"
quick connect to Y terminal on the CCM and
the other end with the 1/4" tab to the yellow/
white wire coming from the low voltage terminal
strip or to the yellow/black wire coming from the
dehumidification logic board if unit has mechanical
dehumidification.
For 3-phase units, connect the wire end with
the 1/4" quick connect to “Y out” on the phase
monitor, and the other end with the 1/4" tab to the
yellow/black wire going to the CCM.
10. Recheck wiring by referring to unit wiring diagram.
11. Apply “This unit equipped with CMA-39 control
module” label to the inside of the inner control
panel cover above the wiring diagram.
12. Replace all panels and covers. This completes the
installation.
13. Turn on power to unit. Check for proper operation
of the unit by referring to
Sequence of
Operation
.
Sequence of Operation
Energize the unit in cooling mode (first or second
stage). The compressor should start (except when
equipped with economizer and enthalpy control is
energizing “free cooling” mode. Energizing Y2 will
override the enthalpy control, allowing the mechanical
cooling to operate). Run the unit for at least 5 minutes.
The condenser fan motor should not run until the
liquid pressure has reached 350 PSI. Should the
liquid pressure fall below 225 PSI while running, the
condenser fan motor will de-energize until the head
pressure builds to 350 PSI.