Carrier WEATHERMASTER 48/50Z030-105 User Manual

Page 128

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128

Adjustments

RETURN/EXHAUST FAN MOTOR PLATE
Adjust using a

-in. wrench on the adjusting bolts:

1. Loosen holddown bolts. (See Fig. 43).
2. Turn the adjusting bolts to move the motor mounting

plate toward or away from the fan to loosen or tighten the

belts. Make the same number of turns to each bolt.

3. Retighten holddown bolts.

SUPPLY FAN AND POWER EXHAUST MOTOR

PLATE — Adjust using a

-in. wrench on the adjusting

bolts:

1. Loosen holddown bolts. (See Fig. 44.)
2. Turn the adjusting bolts to move the motor mounting

plate toward or away from the fan to loosen or tighten the

belts. Make the same number of turns to each bolt.

3. Retighten holddown bolts.

BELT INSTALLATION AND TENSIONING

1. Turn off unit power.
2. Adjust motor plate so belts can be installed without

stretching over the grooves of the pulley. (Forcing the

belts can result in uneven belt stretching and a mis-

matched set of belts.)

3. Before tensioning the belts, equalize belt slack so that it is

on the same side of the belt for all belts. Failure to do so

may result in uneven belt stretching.

4. Tighten belts using the motor plate adjusting bolts.
5. Adjust until proper belt tension (

-in. [13 mm] deflec-

tion with one finger centered between pulleys) is

obtained. Be sure to adjust both adjusting bolts the same

number of turns.
NOTE: Check the tension at least twice during the first

day of operation, as there is normally a rapid decrease in

tension until the belts have run in. Check tension periodi-

cally thereafter and keep it at the recommended tension.

With the correct belt tension, belts may slip and squeal mo-

mentarily on start-up. This slippage is normal and disappears

after wheel reaches operating speed. Excessive belt tension

shortens belt life and may cause bearing and shaft damage.
PULLEY ALIGNMENT — For proper belt life, the motor

and fan pulleys must be properly aligned. To check, first turn

off unit power. Place a straightedge against the motor and fan

pulleys. See Fig. 45. If the pulleys are properly aligned, the

straightedge should be parallel to the belts.

If they are not parallel, check that the motor shaft and fan

shaft are parallel. If they are not, adjust the motor plate adjust-

ing bolts until they are.

After verifying that the shafts are parallel, loosen the set-

screws on the motor pulley. Move pulley on the shaft until the

pulleys are parallel. To move the sheave on the shaft, loosen the

belts. If necessary, blower sheave can also be moved on the

shaft.
INSTALLING REPLACEMENT MOTOR PULLEY (Supply

Fan Only) — To install a field-supplied replacement pulley:

1. Turn off unit power.
2. Loosen belts using motor adjusting bolts until belts can

be removed without stretching them over the grooves of

the pulley.

3. Remove belts.
4. Loosen setscrews on motor pulley.
5. Slide pulley off motor shaft. Make sure setscrews on new

pulley are loose.

6. Slide new pulley onto fan shaft and align it with the fan

pulley as described in Pulley Alignment section above.

7. Tighten setscrews.
8. Install belts and tension properly as described in Pulley

Alignment section above.

CONDENSER FAN ADJUSTMENT (All Units Except

050, 070, 075 Units with High-Capacity Evaporator Coil)

1. Turn off unit power.
2. Remove fan guard and loosen fan hub setscrew.
3. See Fig. 46 and adjust fan height using a straight edge

laid across the fan deck.

4. Tighten setscrew and replace rubber hubcap to prevent

hub from rusting to the motor shaft. Fill hub recess with

Permagum if hub has no rubber hubcap.

5. Replace fan guard.

IMPORTANT: When installing or replacing belts,

always use a complete set of new, matched belts to pre-

vent potential vibration problems. Mixing belts often

results in premature breakage of the new belts.

HOLDDOWN BOLTS

HOLD-
DOWN
BOLTS

Fig. 43 — Return/Exhaust Fan Motor

Plate Adjustment

Fig. 44 — Motor Plate Adjustment

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