Carrier bryant 915SB, Installation, Start-Up, Operating And Service And Maintenance Instructions

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915SB: Installation, Start-up, Operating and Service and Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
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Example : Nominal break point on pressure switch is 0.68-in. W.C. The
minimum break point of the switch is 0.63-in. W.C. The maximum break
point of the switch is 0.73-in. W.C. The maximum make point of the
switch is 0.83-in. W.C.
The electrical ground and polarity for 115-v wiring must be properly
maintained. Refer to Fig. 33 for field wiring information and to Fig. 73
for furnace wiring information.
NOTE: If the polarity is not correct, the STATUS LED on the control
will flashes rapidly and prevent the furnace from heating. The control
system also requires an earth ground for proper operation of the control
and flame-sensing electrode.
The 24-v circuit contains an automotive-type, 3-amp. fuse located on the
control. See Fig. 38 . Any shorts of the 24-v wiring during installation,
service, or maintenance will cause this fuse to blow. If fuse replacement
is required, use ONLY a 3-amp. fuse. The control LED will display
status code 24 when fuse needs to be replaced.
Troubleshooting
Refer to the service label. See Fig. 71 .
The Troubleshooting Guide can be a useful tool in isolating furnace
operation problems. Beginning with the word “Start,” answer each
question and follow the appropriate arrow to the next item. See Fig. 72
The Guide will help to identify the problem or failed component. After
replacing any component, verify correct operation sequence.
Proper instrumentation is required to service electrical controls. The
control in this furnace is equipped with a Status Code LED
(Light-Emitting Diode) to aid in installation, servicing, and
troubleshooting. Status codes can be viewed at the indicator in blower
door. The amber furnace control LED is either ON continuously, rapid
flashing, or a code composed of 2 digits. The first digit is the number of
short flashes, the second digit is the number of long flashes.
For an explanation of status codes, refer to service label located on
control door or Fig. 71 , and the troubleshooting guide which can be
obtained from your distributor.
Retrieving Stored Fault Codes
NOTE: Fault codes cannot be retrieved if a thermostat signal (24-v on
W, Y, G, etc.) is present, or if any delays such as blower off-delays are
active.
The stored status codes will NOT be erased from the control memory
when 115- or 24-v power is interrupted. See the Service Label ( Fig. 71 )
for more information. The most recent fault code may be retrieved as
follows:
1. Leave 115-v power connected to furnace.
2. Observe the status LED through the blower door (the lower door on
upflow applications) indicator. Refer to the Service Label ( Fig. 71 )
to interpret the LED.
3. Remove the Main/Control door (the upper door on upflow
installations).
4. BRIEFLY disconnect and reconnect ONE of the main limit wires.
5. The LED will flash the last stored fault code. Refer to the Service
Label ( Fig. 71 ) to interpret the LED.
6. A component test sequence will follow.
7. Reinstall the Main/Control door.
Component Self-Test
NOTE: The furnace control component test allows all components to
run for a short time; except the gas valve and humidifier terminal HUM
are not energized. The EAC-1 terminal is energized when the blower is
energized. This feature helps diagnose a system problem in case of a
component failure. The component test feature will not operate if any
thermostat signal is present at the control and not until all time delays are
completed.
To Begin Component Self-Test:
1. Remove blower access door.
2. Disconnect the thermostat R lead from furnace control.
3. Manually close blower door switch.
Caution must be taken when manually closing this switch for service
purposes.
4. For approximately 2 sec, short (jumper) the COM-24v terminal on
control to the TEST/TWIN 3/16—in. (5 mm) quick-connect
terminal on control until the LED goes off. Remove jumper from
terminals. See Fig. 38 .
NOTE: If TEST/TWIN and COM-24v terminals are jumpered longer
than 2 sec, LED will flashes rapidly and ignore component test request.
Component test sequence is as follows:
a. LED will display previous status code 4 times.
b. Inducer motor starts and continues to run until Step g of
component test sequence.
c. After 7 sec the hot surface igniter is energized for 15 sec., then
off.
d. Blower motor operates on Continuous-FAN speed for 10 sec.
e. Blower motor operates on HEAT speed for 10 sec.
f. Blower motor operates on COOL speed for 10 sec.
g. Inducer motor stops.
5. Reconnect R lead to furnace control, remove tape from blower door
switch, and re-install blower door.
6. Verify furnace shut down by lowering thermostat setting below
room temperature.
7. Verify that furnace restarts by raising thermostat setting above room
temperature.
Checklist
1. Put away tools and instruments. Clean up debris.
2. Verify that the jumper is removed from the TEST/TWIN terminal.
Verify that there is nothing plugged into the PLT connector. (If there
is a jumper connector plugged into PLT, remove it and discard.) See
Fig. 38 .
3. Verify that the Blower/Heat Off Delay jumpers are set as desired.
See Fig. 38 .
4. Verify that the blower and control (“Main”) doors are properly
installed.
5. Verify that the Status LED glows. If not, check that the power
supply is energized and that the blower door is secure. See Fig. 71 .
6. Cycle test furnace with room thermostat to be sure that it operates
properly with the room thermostat. Check all modes including
Heat, Cool and Fan.
WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
There may be more than one electrical supply to the furnace. Check
accessories and cooling unit for additional electrical supplies that must
be shut off during furnace servicing. Lock out and tag switch with a
suitable warning label.
WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury, or death.
Blower door switch opens 115-v power to furnace control. No
component operation can occur unless switch is closed. Exercise
caution to avoid electrical shock from exposed electrical components
when manually closing this switch for service purposes.