Page 22
mrcool.com
Unit Installation
WARNING
DO NOT
bundle the thermostat wires or lay them side by side, otherwise errors will occur.
1.
High and low voltage wires should be led through different rubber rings of the electric box cover.
2.
High and low voltage wires should be secured separately. Secure the high voltage wires with large clamps
and the lower voltage wires with small clamps.
3.
Use screws to tighten the thermostat wires and power cords of the units on the terminal board. If the
power cords and thermostat wires are improperly connected, it could create a fire hazard and the air
conditioner may suffer damage.
4.
Ground the units by connecting the ground wire and ensure it is secure.
5.
The units should comply with applicable local and national rules and regulations on power consumption.
6.
When connecting the power cord, make sure the phase sequence of the power supply matches with the
corresponding terminals, otherwise the compressor will get reversed and operate abnormally.
Connecting the Power Cord & Communication Wire
Electrical Connection
Electrical wiring of Single-phase unit: MDUI18048/MDUI18060 (4-5 Ton Unit w/electric heater)
Optional: Heat Kit Installation Instructions
Circuit Breaker Size in Panel
for Air H Heat Kit
Combination
Max Amperage
MDUI 48K/60K + MHK15U
60/30 Amps
60/60 Amps
MDUI 48K/60K + MHK20U
Circuit
Breaker Panel
15 KW and 20 KW
Heat Kit
See Note
NOTE
: A Heat Kit Installation
is
NOT
required for the unit
to function properly. It is
intended for
Emergency
Heating Purposes
ONLY
.
L1
L2
Breaker
Molex Plug
Wiring Harness
L1
L2
Breaker
Fig. 2.18
1.
Remove the upper access panel from the air
handler.
2.
Remove the cover plate inside the upper access
panel of the air handler.
3.
Slide the heat kit into the slot and secure
element plate with previously removed screws.
4.
Make sure to insert the supporting poles of the
heat kit into the supporting hole of the air handler.
5.
Connect the quick connection plug and fasten
the loose wires by using wire ties.
6.
Install the circuit breaker into the mounting rail,
break out appropriate area of the plastic circuit
breaker cover on the air handler access panel.
7.
a.
When installing the MHK15U or MHK20U,
connect two separate lines of power from the
Circuit Breaker Panel to L1 and L2 of the two circuit
breakers included with the electric heat kit.
b.
When connecting the electric heat kit to the
air handler, use the Molex Plug Wiring Harness
from the electric heat kit and attach it to the Molex
Plug Wiring Harness coming from air handlers PCB
board.
c.
The Molex Plug Connection will power the air
handler, so a separate source of incoming power
for the air handler itself is not needed.
d.
Please see the chart below for proper sizing
of panel.