Install Manual

Page 30

mrcool.com

Unit Installation

Electrical wiring of Single-phase unit: MDUO18024036 & MDUO18048060

Electrical Connection

Connecting the Power Cord & Thermostat Wire

Fig. 2.31-A

Power

Breaker

208/230V L1

1PH L2

60HZ G

Indoor

Unit

Thermostat

LEGEND:

Y- Compressor control signal

B- is energized under the heating mode, means 4-way valve

control

D- defrosting signal

R- 24V AC power supply

C- 24V common

NOTE: When the outdoor unit defrosts, D will send an operation

signal to the electric heater to avoid cold winds. However, the

indoor fan should operate continuously, which is controlled by

the wire controller.

NOTE: As for the indoor units, which do not include D, there is no

need to connect the D terminals.

DO NOT bundle up the temperature thermostat wires and power 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.

3. Use screws to tighten the power cord and thermostat wire of the units on the terminal board. An

improper connection could create a ﬁre hazard.

4. If the power cord and thermostat wires are not correctly connected, the air conditioner may suﬀer

damage.

5. Ground the units through connecting the ground wire and ensure it is secure.

6. The units should comply with applicable local and national rules and regulations on power

consumption.

7. 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.

WARNING