Owner Manual

Page 22mrcool.com
Unit Installation
WARNING
1. High and low voltage wires should be led through different rubber rings of the electric box cover.
2. Do not bundle the thermostat wires or lay them side by side, otherwise errors will occur.
3. High and low voltage wires should be secured separately. Secure the former ones with large clamps and the
latter ones with small clamps.
4. Use screws to tighten the power cords and thermostat wires of the units on the terminal board. Improper
connection may create a fire hazard.
5. If the power cords and thermostat wires are not correctly connected, the air conditioner may suffer damage.
6. Ground the units by connecting the ground wire.
7. The units should comply with applicable local and national rules and regulations on power consumption.
8. 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.
Electrical Connection
Connecting the Power Cord & Thermostat Wire
Electrical wiring of Single-phase unit: MDUI18048/MDUI18060
Optional: Heat Kit Installation Instructions
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 access panel of the air handler.
7. a.When installing the MHK15U and 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 give power to air
handler, meaning you will not need a separate source
of incoming power for the air handler itself.
d. Please see the chart below for proper sizing of panel.
Circuit Breaker Size in Panel for Air Handler + 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 for
Emergency Heat Purposes
ONLY.
L1 L2
Breaker
Molex Plug
Wiring Harness
L1 L2
Breaker
Fig. 2.13