Bryant 542J Series, Installation, Start-Up And Service Instructions Manual

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IV. INDOOR FAN SERVICE AND REPLACEMENT
A. 542J150 Units (Fig. 28)
NOTE: To remove belts only, follow Steps 1-6.
1. Remove filter and supply-air section panels.
2. Remove unit top cover.
3. Loosen carriage nuts A and B holding motor mount as-
sembly to fan scroll side plates.
4. Loosen screw C.
5. Rotate motor mount assembly (with motor attached)
as far as possible away from indoor coil.
6. Remove belt.
7. Rotate motor mount assembly back past original posi-
tion toward indoor coil.
8. Remove motor mounting nuts D and E (both sides).
9. Lift motor up through top of unit.
10. Reverse Steps 1-9 to reinstall motor.
11. Check and adjust belt tension as necessary.
B. 542J180 Units (See Fig. 29)
The 180 units use a fan motor mounting system that fea-
tures a slide-out motor mounting plate. To replace or service
the motor, slide out the bracket.
1. Remove the indoor-fan access panel and the heating
control access panel.
2. Remove the center post (located between the indoor fan
and heating control access panels) and all screws se-
curing it.
3. Loosen nuts on the 2 carriage bolts in the motor mount-
ing base.
4. Using jacking bolt under motor base, raise motor to top
of slide and remove belt. Secure motor in this position
by tightening the nuts on the carriage bolts.
5. Remove the belt drive.
6. Remove jacking bolt and tapped jacking bolt plate.
7. Remove the 2 screws that secure the motor mounting
plate to the motor support channel.
8. Remove the 3 screws from the end of the motor sup-
port channel that interfere with the motor slide path.
9. Slide out the motor and motor mounting plate.
10. Disconnect wiring connections and remove the 4 mount-
ing bolts.
11. Remove the motor.
12. To install the new motor, reverse Steps 1-11.
13. Check and adjust belt tension as necessary.
V. ECONOMIZER ADJUSTMENT
See Tables 11 and 12 for checkout and enthalpy simulation.
Make certain the outdoor-air damper is fully closed and the
return-air damper is fully open before completing the follow-
ing steps:
1. Turn on power to the unit.
2. Turn the thermostat fan switch to the ON position. The
damper will go to the vent position.
3. Adjust the vent position with the minimum position
adjustment on the economizer motor control module.
See Fig. 17.
4. Set the system selector switch to COOL position and
set the cooling temperature selector to its lowest
setting.
Table 11 — Economizer Checkout Procedures
TEST PROCEDURE RESULTS
A. Disconnect power at
TR and TR1.
Disconnect jumper
between P and
P1. See Fig. 17.
B. Jumper TR to 1.
C. Jumper T1 to T.
D. Disconnect outdoor-air
thermostat connections
from S
O
and +.
Factory-installed
800 ohm resistor
should remain connected
to S
R
and +.
E. Reconnect power to
terminals TR and TR1.
1. LED (light-emitting diode)
should be off.
2. Motor is in closed position.
TEST PROCEDURE RESULTS
Disconnect factory-installed
resistor from terminals
S
R
and +.
1 LED (light-emitting diode)
should be on.
2. Motor drives toward open.
Table 12 — High and Low Outdoor-Air Simulation
TEST PROCEDURE RESULTS
A. Reconnect factory-installed
800 ohm resistor
between terminals
S
R
and +.
B. Connect 1200 ohm
checkout resistor between
terminals S
O
and +.
C. Turn set point potentiometer
to position A.
Low outdoor air temperature
test results:
1. LED (light-emitting diode)
should be on.
2. Motor drives toward open.
D. Turn set point potentiometer
to position D.
E. Disconnect 1200 ohm
checkout resistor.
High outdoor air temperature
test results:
1. LED should be off.
2. Motor drives toward closed.
NOTE: The cooling mode may also be simulated by remov-
ing the thermostat wires from terminals Y1 and Y2 and in-
stalling a jumper between terminals R and Y1. Refer to unit
label diagram for terminal locations.
5. Set the outdoor-air thermostat (OAT), located in the
economizer section of the unit to 75 F.
6. If the outdoor temperature is below 75 F, the econo-
mizer will control the leaving air with the mixed-air
sensor. If the outdoor air is above 75 F, place a jumper
around the contacts of the OAT.
7. Jumper terminal T to terminal T1 on the module (see
Fig. 17). The economizer will go to the full open posi-
tion. The outdoor-air damper will go to the full open
position, and the return-air damper will go to the full
closed position.
8. Adjust mechanical linkage, if necessary, for correct po-
sitioning. It may be necessary to remove the filters to
adjust the linkage.
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