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284ANV: Installation Instructions
Outdoor Coil Thermistor
The outdoor coil thermistor is a 10Kohm resistor used for multiple
system operations. It provides the coil/liquid line temperature to the
primary control module and user interface. It is used for low ambient
operation, defrost initiation, defrost termination and assistance with OAT
temperature measurement. The sensor must be securely mounted to the
tube connecting the EXV and distributor.
placement. See
Table 5
for proper resistances.
Fig. 29 – Outdoor Coil Thermistor Mounted on Coil
Suction Thermistor (OST)
Suction Thermistor is used for assisting in EXV control and must be
secured on the suction tube and aligned longitudinally to the vertical
surface of the tube axis (see
Fig.
Discharge Thermistor (ODT)
Discharge thermistor is used for protection against over temperature of
the compressor and the discharge superheat calculations.
mounting is required to ensure that the unit exits the start-up mode. The
ODT is located on the compressor discharge stub-out (see
Fig. 30 – Suction Thermistor (OST) and Discharge Thermistor
(ODT) Mounting Locations
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
See
Fig. 29
for proper
30).
Fig.
30).
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage and/or
improper operation.
In order to minimize the ambient influence, make sure the thermistor
curved surface hugs the pipe surface and is secured tight using the wire
tie fished through the original slot, insulating polymer body.
Failed Thermistor Default Operation
Factory defaults have been provided in the event of failure of outdoor air
thermistor (OAT) and/or outdoor coil thermistor (OCT).
If the OAT sensor should fail the outdoor unit will operate at a fixed
speed. Defrost will be initiated based on coil temperature and time.
If the OCT sensor should fail the outdoor unit will operate at a fixed
speed. Defrost will occur at each 60 minute time interval during heating
operation, but will terminate after 10 minutes.
If the OST should fail then the outdoor unit will continue to operate in
cooling without modification, but heating operation will not be allowed.
Variable Speed Compressor Winding Resistance
This compressor operates with 3-phase variable frequency PWM
variable voltage. For troubleshooting certain fault codes
compressor resistances, follow these steps:
1. Disconnect compressor power leads from the inverter terminals,
U (YEL), V (RED), and W (BLK).
2. Measure the resistance between YEL to RED, YEL to BLK, and
A200046
RED to BLK and compare to
should be equal.
3. Measure the resistance to ground for each lead.
4. If the resistances are correct then reconnect power leads to
appropriate terminal.
5. If the resistances appear to be abnormal, it will be necessary to
measure the resistance at the compressor fusite terminals.
6. Remove the sound blanket and harness plug, measure the
resistances, and compare to
Proper
7. Reinstall compressor sound blanket making sure discharge
thermistor and compressor power harness are routed as they were
from the factory
Table 7 – Variable Speed Compressor Resistances
(winding resistance at 68°F? (20°F)
WINDING
Between terminals
T1, T2, and T3
Between terminal &
ground
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage and/or
improper operation.
Do not use Meggar for measuring the winding resistance.
A200047
Fan Motor
The fan motor requires 5 wires connected to VFD for operation. These
wires are: DC BUS, GND, +15V DC, Vsp, FG. Note high voltage may
be present on ALL wires because they are not earth or chassis ground
referenced. Do not attempt to measure voltages while running. Fan
speed is monitored by VFD and PCM continuously. If fan faults occur
verify the fan blade rotates freely without obstruction.
electrical connections are secure and wires are undamaged.
Status Codes
17
CAUTION
!
Table 7
values. Each resistance set
Table
7.
24
36
48
.74
.453
.424
>1 mega OHM
CAUTION
!
related to
60
.424
Ensure all
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