Specifications

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
PC 111 Catalog No. 533-80124 Printed in U.S.A. Form 38-57SI Pg 1 4-05 Replaces: 38-1SI
38-55SI
Book 1 4
Ta b 3 e 2 f
Cancels: IIK 538-09-1 IIK 538-09-8
IIK 538-09-7 4/1/05
Installation Instructions
Part Number 53DS-900---060
NOTE: Read and become familiar with these instructions
before beginning installation.
SAFETY CONSIDERATIONS
Installing and servicing air-conditioning equipment can be
hazardous due to system pressures and electrical components.
Only trained and qualified personnel should install or service
air-conditioning equipment. When working on air-conditioning
equipment, observe the precautions provided in literature, tags,
and labels attached to the unit.
GENERAL
These instructions cover the installation of low ambient
temperature controller accessory kit on the duct-free cooling
and heat pump condensing units.
The low ambient temperature head pressure controller
(HPC) is a fan control device activated by a high cycle rate
pressure switch. It is specifically designed for use with duct-
free systems, cooling only and heat pump units. The low
ambient temperature controller is designed to maintain a con-
densing pressure of 200 to 225 psig by cycling the outdoor-fan
motor. No field adjustments or calibrations are required.
All of the components necessary for installing the low
ambient temperature controller are included in the package.
This kit consists of a pressure switch and installation instruc-
tions. When unpacking the accessory, carefully inspect for
shipping damage. If damage is evident, return for replacement.
INSTALLATION
Step 1 — Mount Pressure Switch
1. Place 3 drops of compressor oil in the pressure switch for
lubrication.
2. Mount the pressure switch as shown in Fig. 1-3.
3. Coil up the excess wire and secure next to the pressure
switch.
Step 2 — Connect Power Wiring — All wiring must
comply with local codes and National Electrical Code (NEC)
requirements. See Fig. 4 for accessory wiring.
NOTE: An adapter tube is required for the 38CG024 unit.
Electrical shock can cause personal injury or death. Before
beginning any modification or installation of this kit, be
sure the main electrical disconnect is in the off position.
Ensure power is disconnected to the fan coil unit. On some
systems both the fan coil and the outdoor unit may be on the
same disconnect. Tag the disconnect switch with a suitable
warning label. There may be more than one disconnect.
IMPORTANT: Heat pump models require an isolation
relay (part numbers HN61KK066 for a 24-v coil,
HN61KK912 for a 120-v coil, HN61KK913 for a
240-v coil) to prevent fan cycling in heat pump mode.
The low ambient temperature controller must be
installed in conjunction with the accessory wind baf-
fle. An accessory winter start control (part number
KAAWS0101AAA) is recommended (cooling only
018-060 units) when low outdoor temperatures may be
encountered or when nuisance tripping of the
low-pressure switch (factory installed) may be
encountered.
The winter-start control package consists of a time-de-
lay that must be wired across the low-pressure switch.
The time-delay relay will bypass the low-pressure switch
for 3 minutes on start-up before the low-pressure switch
becomes part of the control circuit.
A crankcase heater is also recommended when using
low ambient temperature control.
Duct-Free Systems
Cooling Only and Heat Pump Units
Low Ambient Temperature Controller Accessory
LOW AMBIENT
TEMPERATURE
CONTROL
SERVICE PORT
DISCHARGE LINE*
*For 38BN units the service port is on the liquid line.
Fig. 1 — Low Ambient Temperature Control
Location (38HDC,HDL,QR,SB,SC,CG, 38CS030,
38BK018-024, 38BN, 538A,B,J)