Carrier 38AU User Manual

Page 17

Fig. 14 — Weatherproof Cover Installation

All Units —
Voltage to compressor terminals during operation must be

within voltage range indicated on unit nameplate. See Tables

10 and 11. On 3-phase units, voltages between phases must be

balanced within 2% and the current within 10%. Use the

formula shown in the legend for Tables 10 and 11, Note 5 (see

page 19) to determine the percent of voltage imbalance.

Operation on improper line voltage or excessive phase

imbalance constitutes abuse and may cause damage to

electrical components. Such operation would invalidate any

applicable Carrier warranty.
Field Control Wiring — 38AU unit control voltage is 24 v.

See Figs 23 and 24 for typical field control connections and the

unit’s label diagram for field-supplied wiring details. Route

control wires to the 38AU unit through the opening in unit’s

end panel to the connections terminal board in the unit’s

control box.
Remainder of the system controls connection will vary

according to the specific construction details of the indoor

section (air handler or packaged fan coil). Figs 15 (38AUZ)

and 16 (38AUD) depict typical connections to a Carrier 40RU

fan coil unit. Plan for field connections carefully and install

control wiring correctly per the project plan. Additional

components and supplemental transformer accessory may be

required.
The 38AU unit requires an external temperature control device.

This device can be a thermostat (field-supplied) or a

PremierLink controller (available as a field-installed accessory,

for use on a Carrier Comfort Network or as a stand alone

control).
Thermostat —
Install a Carrier-approved accessory thermostat according to

installation instructions included with the accessory. Locate the

thermostat accessory on a solid wall in the conditioned space to

sense average temperature in accordance with the thermostat

installation instructions.
38AUZ Unit – 38AUZ unit is a single-stage cooling unit. If no

economizer function is required, select a single-stage cooling

thermostat. If an integrated economizer function is required,

select a two—stage cooling thermostat.
38AUD Unit – 38AUD unit is a two-stage cooling unit. Select

a two-stage cooling thermostat.
Select a thermostat cable or equivalent single leads of different

colors with minimum of four leads for 38AUZ unit or five

leads for 38AUD units. Check the thermostat installation

instructions for additional features which might require

additional conductors in the cable.

For wire runs up to 15 m (50 ft.), use no. 18 AWG (American

Wire Gage) insulated wire (35°C minimum). For 15 to 23 m

(50 to 75 ft.), use no. 16 AWG insulated wire (35°C minimum).

For over 23 m (75 ft.), use no. 14 AWG insulated wire (35°C

minimum). All wire sizes larger than no. 18 AWG cannot be

directly connected to the thermostat and will require a junction

box and splice at the thermostat.
PremierLink (accessory installation) – Refer to Form 33CS-

58SI for details on connecting the PremierLink controller and

its various sensors.

Fig. 15 — Typical Remote Thermostat Connections

— 38AUZ

Fig. 16 — Typical Remote Thermostat Connections

— 38AUD

RECEPTACLE
NOT INCLUDED

COVER – WHILE-IN-USE
WEATHERPROOF

BASE PLATE FOR
GFCI RECEPTACLE

Note 1: Typical multi-function marking. Follow manufacturer’s configuration

instructions to select Y2.

Note 2: Y2 to economizer required on single-stage cooling units when

integrated economizer function is desired

Note 3: Connect only if thermostat requires 24-vac power source.

Note 4: Connect W1 and W2 if supplemental heaters are installed

Field Wiring

O/B/Y2

(Notes 1, 2)

(Note 3)

(Note 4)

Note 1: Typical multi-function marking. Follow manufacturer’s configuration

instructions to select Y2.

Note 2: Connect only if thermostat requires 24-vac power source.

Note 3: Connect W1 and W2 if supplemental heaters are installed

Field Wiring

O/B/Y2

(Notes 1)

(Note 3)