Bryant 180CNV024 - Page 12

12
ECM Fan Motor
If verification of proper operation is required for the ECM motor
used in this unit, follow these steps:
1. Verify that the 230v input to the transformer is present.
2. Verify that the control board is powered 18 volts to 30 volts
from the transformer.
3. With the UI in charging mode in cooling, measure the DC
voltage between the PWM 1 and PWM 2 terminals on the
outdoor control board. The DC voltage and PWM (option-
al) measured must be as shown in Table 6.
Table 6 – DC Voltage and PWM Measurement
Unit Size Voltage PWM
24, 36 8.9 VDC 52
48, 60 11.1 VDC 84
Status Codes
Table 7 shows the status codes flashed by the amber status light.
Most system problems can be diagnosed by reading the status code
as flashed by the amber status light on the control board.
The codes are flashed by a series of short and long flashes of the
status light. The short flashes indicate the first digit in the status
code, followed by long flashes indicating the second digit of the
error code.
The short flash is 0.25 seconds ON and the long flash is 1.0 second
ON. Time between flashes is 0.25 seconds. Time between short
flash and first long flash is 1.0 second. Time between code
repeatin g is 2.5 seconds with LED OFF.
Codes are easily read from wall control.
EXAMPLE:
3 short flashes followed by 2 long flashes indicates a 32 code.
Table 7 shows this to be low pressure switch open.
Emergency Mode Connections with a Conventional
Thermostat
In an emergency, it is possible to replace the wall control with a
conventional thermostat. The unit will operate in maximum
cooling speed only.
D
C
B
A
User Interface (UI)
D
C
B
A
No
Use
C
B
A
VS AC
OAT
RYOWCHUM
C
Humidifier
24vac
C and D
not required on
VS air conditioner
Furnace or Fan Coil
A12055
Fig. 14 -- Evolutio n Furnace or Fan Coil Wiring with Com-
municating Va riable Speed AC
D
C
B
A
VS AC
OAT
GYOWCHUM
Furnace or Fan Coil
C
B
A
NO
USE
UT
IL
C
LS
O
Y
R
GYOWC R
Conventional
Dual-Fuel
Thermostat
A11382
Fig. 15 -- Variable Speed Unit Connected to a Conventional
Dual Fuel Thermostat in an Emergency Mode