Manual 2100-614K
Page 6 of 61
LOW VOLTAGE FIELD WIRING
The MC4002 is powered from the air conditioners that it
is controlling, 24 VAC (18-32V) low voltage only.
Circuitry in the MC4002 isolates the power supplies of
the two air conditioners so that no back feeds or phasing
problems can occur. Additionally, if one air conditioner
loses power, the MC4002 and the other air conditioner
are unaffected and will continue to operate normally.
Connect the low voltage eld wiring from each unit per the
low voltage eld wiring diagrams in Section on “Controller
Wiring”. NOTE: Maximum of 18-gauge control wiring
should be used. Using heavier gauge wiring can create
excessive stress on the control board as door is opened
and closed. Create a wiring loop so the door can open
and close without stressing terminal blocks.
CONTROLLER GROUNDING
A reliable, veried earth ground must be connected
in addition to any grounding from conduit. Grounding
lugs are supplied for this purpose. All other alternative
grounding methods must meet all applicable national,
state and local codes per the product application.
CONTROLLER POWER-UP
Whenever power is rst applied to the controller, there
is a twenty (20) second time-delay prior to any function
(other than display) becoming active. This time-delay
is in effect if the controller On/Off button is used
when 24VAC from air conditioners is present, and also
if controller is in “ON” position and 24VAC from air
conditioners is removed and then restored.
FIRE SUPPRESSION CIRCUIT
To disable the MC4002 and shut down both air
conditioners, terminals F1 and F2 may be used. The F1
and F2 terminals must be jumpered together for normal
operation. A normally closed (nc) set of dry contacts may
be connected across the terminals and the factory jumper
removed for use with a eld-installed re suppression
system. The contacts must open if a re is detected.
See appropriate connection diagram - Figures 1, 2 or 3
for this connection. Contacts should be rated for pilot
duty operation at 2 amp 24VAC minimum. Shielded wire
(22-gauge minimum) must be used, and the shield must
be grounded to the controller enclosure.
SPECIFICATIONS/FEATURES FOR
ALARM BOARDS
MC4002-A w/Optional Base Alarm Board
(Inputs/Outputs)
NOTE: If this alarm board was not originally
factory installed, it can be field-installed at
anytime. Bard part number is AB3000-B.
NOTE: If this alarm board was not originally factory
installed, it can be field-installed at anytime. Bard
part number is AB3000-A.
Inputs
Lockout 1 2,3 – input from HVAC #1
Lockout 2 2, 3 – input from HVAC #2
Outputs
Smoke/Fire Form C (SPDT)
Lockout 1 Form C (SPDT)
Refrigerant alarm HVAC #1
Lockout 2 Form C (SPDT)
Refrigerant alarm HVAC #2
Power Loss 1 Form C (SPDT)
Power loss HVAC #1
Power Loss 2 Form C (SPDT)
Power loss HVAC #2
Low Temp Form C (SPDT)
Low temperature alarm
High Temp 1 Form C (SPDT)
High temperature alarm #1
MC4002-B w/Enhanced Version Alarm Board
(Additional Outputs) plus MC4002-A Inputs/Outputs
Alarm relays can be wired for NO (close on alarm) or NC (open on alarm) strategy. Alarm relays can be used individually
if there are enough available building alarm points, or can be arranged into smaller groups or even a single group so that
all alarm capabilities can be utilized. When multiple alarms are grouped together and issued as a single alarm there will
be no off-site indication of which specific problem may have occurred, only that one of the alarms in the group has been
triggered. The individual alarm problem will be displayed on the LED display on face of the controller.
High Temp 2 Form C (SPDT)
High temperature alarm #2
Controller Form C (SPDT)
Controller failure alarm – see note (a)
Econ 1 E, F - Form A (NO) – see note (b)
Econ 2 E, F - Form A (NO) – see note (b)
2
nd
Stage Form C (SPDT) – see note (c)
2
nd
-stage cooling alarm
(a) Alarm will only activate if main board processor
fails or if alarm board to main board cable is damaged.
(b) Make these connections to terminals E & F
in HVAC 1 and 2 respectively if desired to have
economizers open for emergency ventilation at High
Temp Alarm #2 setpoint condition.
(c) For units with 2-stage compressors, 2nd stage
cooling alarm activates on cooling Stage 3 initiation.
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