Carrier WeatherMaker 50TC 17-30 Series, Service And Maintenance Instructions

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Adjusting the Belt Tension
Use the following steps to adjust the V-belt tension. See Fig. 6.
1. Loosen the four motor mounting nuts that attach the motor to
the blower rail.
2. Loosen the two jack bolt locking nuts beneath the motor
mounting plate. Turn the jack bolt locking nut counterclock -
wise to loosen.
3. Turn the jack bolts counterclockwise to loosen and clockwise
to tighten.
4. Adjust the V-belt for proper tension.
5. Make sure the fan shaft and motor shaft are parallel before
tightening the motor mount nuts. See Fig. 6.
6. Make adjustments as necessary.
7. Tighten the four motor mounting nuts.
8. Check the V-belt tension. Make adjustments as necessary.
9. Re-tighten the four motor mounting nuts.
10. Tighten both jack bolt locking nuts securely.
Replacing the V-belt
1. Use a belt with same section type or similar size. Do not sub -
stitute a “FHP” or notched type V-belt.
2. Loosen (turn counterclockwise) the motor mounting plate
front bolts and rear bolts. See Fig. 7.
3. Loosen (turn counterclockwise) the jack bolt lock nuts.
Loosen (turn counterclockwise) the jack bolts, relieving the
belt tension and allowing easy removal of the belt by hand.
4. Remove the belt by gently lifting the old belt over one of the
pulleys.
5. Install the new belt by gently sliding the belt over both pul -
leys, then tighten (turn clockwise) the jack bolts, sliding the
motor plate away from the fan housing until proper belt ten -
sion is achieved.
6. Check the alignment of the pulleys, adjust if necessary. See
Fig. 6.
7. Tighten all bolts attaching the motor to the motor plate.
8. Tighten all jack bolt jam nuts by turning clockwise.
9. Check the tension after a few hours of runtime and re-adjust
as required. See Fig. 7.
Fig. 6 — Checking Blower Motor Belt Tension
Fig. 7 — Belt Drive Motor Mounting
ADJUSTABLE-PITCH PULLEY ON MOTOR
The motor pulley is an adjustable-pitch type that allows a servicer
to implement changes in the fan wheel speed to match as-installed
ductwork systems. The pulley consists of a fixed flange side that
faces the motor (secured to the motor shaft) and a movable flange
side that can be rotated around the fixed flange side that increases
or reduces the pitch diameter of this driver pulley. (See Fig. 7.)
As the pitch diameter is changed by adjusting the position of the
movable flange, the centerline on this pulley shifts laterally, along
the motor shaft. This creates a requirement for a realignment of
the pulleys after any adjustment of the movable flange. Also reset
the belt tension after each realignment. The factory settings of the
adjustable pulley is five turns open from full closed.
Check the condition of the motor pulley for signs of wear. Glazing
of the belt contact surfaces and erosion on these surfaces are signs
of improper belt tension and/or belt slippage. Pulley replacement
may be necessary.
Changing Fan Speed
1. Shut off the main unit power supply, and use the approved
lockout/tag-out procedures.
2. Loosen the belt by loosening the motor adjustment bolts as
described in the Belt Adjustment section.
3. Loosen the movable pulley flange setscrew. (See Fig. 7.)
4. Screw the movable flange toward fixed flange to increase
speed and away from fixed flange to decrease speed.
CAUTION
EQUIPMENT DAMAGE HAZARD
Failure to follow this CAUTION can result in premature wear
and damage to equipment.
Do not use a screwdriver or a pry bar to place the new V-belt in
the pulley groove. This can cause stress on the V-belt and the
pulley resulting in premature wear on the V-belt and damage
to the pulley.
BROWNING BELT
TENSION CHECKER
STRAIGHTEDGE
1/2”
(1.3 cm)
BELT
DEFLECTION
MOTOR
V-BELT
MOTOR ADJUSTMENT
BOLTS (4)
JACKBOLT LOCKING NUT (2)
MOTOR MOUNTING PLATE
JACKBOLT (2)