Carrier 58SSB - Manual (Page 6)

HEATING SPEED
TRIM POT
TO BLOWER'
A WARNING
To avoid possibility of electrical shock, be sure to
disconnect electrical power before removing access
panels.
Fig. 8 — Variable Speed Blower Interface Board
TEMPERATURE RISE ADJUSTMENT
Furnace must not be operated outside range of tem­
perature rise specified on unit rating plate. Determine
air temperature rise as follows;
1. Place thermometers in return and supply ducts as
near furnace as possible. Be sure thermometers do not
see heating element so that radiant heat does not
affect readings. This practice is particularly important
with straight run ducts.
2. When thermometer readings stabilize, subtract return-
air temperature from supply-air temperature to deter­
mine air temperature rise.
NOTE: If outdoor section and system thermostat are
not installed, temperature rise can be determined by
jumpering R and W circuits on furnace control board.
3. Adjust temperature rise to midpoint of temperature
rise range specified on unit rating plate by adjusting
blower speed. To adjust blower speed locate heating
speed trimpot in interface circuit board (see Fig. 8).
Increase blower speed clockwise to reduce tempera­
ture rise. Decrease blower speed counterclockwise to
increase temperature rise.
CARE AND MAINTENANCE
A CAUTION
Because of possible damage to the equipment or
personal injury, maintenance should be performed
by qualified persons only.
For long life, economy and high efficiency, clean
accumulated dirt and grease from blower wheel and
motor annually.
The following steps should be performed by a qualified
service person:
Some motors have prelubricated sealed bearings and
require no lubrication. These motors can be identified
by the lack of oil ports on each end of the motor. For
those motors with oil ports:
Lubricate motor every 5 years if motor is used on inter­
mittent operation (thermostat FAN switch in AUTO,
position), or every 2 years if motor is in continuous
operation (thermostat FAN switch in ON position).
Clean and lubricate as follows:
1. Remove access panels.
2. Disconnect R, W, and C thermostat leads on furnace
control board.
3. Remove control box from bottom side of blower
shelf and position out of way.
4. Note location of wires for reassembly. Remove elec­
trical leads from numbered panel mount connector
located on left side of interface box.
5. Disconnect 15-conductor cable on interface circuit
board.
6. Note location of thermostat wires for reassembly.
Remove electrical leads from terminal block,TB4 on
interface circuit board.
7. Remove cover of auxiliary junction box. Disconnect
power leads going to interface circuit board.
8. Remove screws securing blower assembly to blower
shelf and slide blower assembly out of furnace.
9. Squeeze release tabs on connector PL2 and pull from
ECM blower controller.
10. Mark blower wheel location on shaft and motor
support location on motor before disassembly to
ensure proper reassembly.
11. Loosen setscrew holding blower wheel on motor
shaft.
12. Remove bolts holding motor mount to blower hous­
ing. Slide motor and mount out of housing.
13. Lubricate motor.
a. Remove dust caps or plugs from oil ports located
at each end of motor. If motor does not have these
caps or plugs, bearings are sealed and need no
further lubrication.
b. Use a good grade of SAE 20 nondetergent motor
oil. Put one teaspoon (5 cc, 3/16 oz or 16 to 25
drops) in each oil port. Use of other types or
grades of oil will damage motor. Excessive oiling
can cause premature bearing failures.
c. Allow time for total quantity of oil to be absorbed
by each bearing.
d. After oiling motor, wipe excess oil from motor
housing.
e. Replace dust caps or plugs on oil ports.
14. Remove blower wheel from housing.
a. Mark blower wheel orientation and cutoff plate
location to ensure proper reassembly.
b. Remove screws securing cutoff plate and remove
cutoff plate from housing.
c. Remove blower wheel from housing.
15. Clean blower wheel and motor by using a vacuum
with soft brush attachment. Be careful not to disturb
balance weights (clips) on blower wheel vanes. Do
not drop or bend wheel because balance will be
affected.
16. Reassemble blower by reversing steps 14a through c.
Be sure wheel is positioned for proper rotation and
motor oiling plugs are pointed up when motor is
installed.