Electronic Expansion Valve (Exp); Outdoor Fan Motor; Pressure Transducer (Spt); Pressure Equalizer Valve (Pev) - Bryant 189BNV EVOLUTION Service Manual

CAUTION
!
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage
and/or improper operation.
Do not attempt to apply line voltage directly to the
compressor. This will destroy the compressor.
Electronic Expansion Valve (EXV)
This unit uses an electronic expansion valve for refrigerant
metering in the heating mode. The control board drives the EXV to
its proper position based on the operating mode and conditions.
The Evolution Connex Control Service mode allows for manual
opening and closing of the EXV for troubleshooting and pump
down.

Outdoor Fan Motor

The compact ECM outdoor fan motor is a variable- -speed brushless
DC (BLDC) motor that operates at speeds from 400 to 1050 RPM.
The motor is a 3- -phase permanent magnet- -type motor. Just like
the compressor, this motor speed is determined by the inverter
output frequency and amplitude.
Motor speed is controlled through the inverter board in the outdoor
unit and no electronic module is attached. Motor speed is slowed as
the building load decreases, maintaining the proper condensing
temperature for both cooling and dehumidification. As the building
load increases, the motor will increase speed until it is at maximum
speed at the maximum building load.
At unit start- -up, there is a slight delay and thrust motion of the fan
motor/blade in the reverse direction, prior to ramping- -up the fan
assembly.

Pressure Transducer (SPT)

A 5 VDC output low pressure transducer that provides a 0- -5 VDC
data for interpretation by the control board for a 0 to 200 psig
range of pressure at the suction tube. This interpreted pressure data
is then intelligently used by the AOC control board for low
pressure cut- -out, loss of charge management, compressor
protection, oil circulation management, lubrication management
and EXV control.

Pressure Equalizer Valve (PEV)

At the end of every compressor operation (after the 3.5 minute
Time Guard period), the equalizer valve opens for 150 seconds
plus an additional 15 seconds of protection before allowing the
compressor to start ramping up.
The PEV is located next to the suction and discharge of the
compressor. The function of this valve is to prevent the
compressor from starting with a high refrigerant pressure
differential, thus helping the reliability of the compressor.
NOTE: A hissing sound may be heard during the equalization
process. This is normal.

Outdoor Coil Thermistor (OCT)

The outdoor coil thermistor is a 10Kohm resistor used for multiple
system operations. It provides the coil/liquid line temperature to
the heat pump board and user interface. Low ambient operation,
defrost initiation, defrost termination and assistance with OAT
temperature measurement of some of the functions (see Fig.4) .
The sensor must be securely mounted to the tube connecting the
EXV and distributor. See Fig. 2 and Fig. 3 for proper placement.
See Table 5 for proper resistances.
Fig. 2 – HP Outdoor Coil Thermistor (OCT) Attachment
(On Distributor Tube)
Fig. 3 – AC Outdoor Coil Thermistor (OCT) Attachment
(On Distributor Tube)
OAT Thermistor must be locked in place with
spherical nib end facing towards the front of
the control box
Fig. 4 – OAT Thermistor Location (Bottom of Control Box)
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