Carrier NP034-074 Adjustments, Belt Installation and Tensioning, Condenser FAN Adjustment

Adjustments

EVAPORATOR FAN AND POWER EXHAUST MOTOR PLATE Ð Adjust using a 15¤16-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.

MODULATING POWER EXHAUST DIFFERENTIAL PRESSURE SWITCH Ð On 034,044 units, the differential pressure switch is located in the auxiliary control box. The auxiliary control box is mounted in the corner next to the power exhaust motor door. To gain access to the auxiliary control box, remove the auxiliary control box cover. When replacing the auxiliary control box cover, be sure to secure the cover properly in order to prevent water from being drawn into the auxiliary control box.

On 054-074 units, the differential pressure switch is mounted below the auxiliary control box next to the access door la- beled FILTER SECTION.

INLET GUIDE VANE DIFFERENTIAL PRESSURE SWITCH (Units With Optional Inlet Guide Vanes and Static Pressure Control) Ð On 034,044 units, the inlet guide vane differential pressure switch is located in the auxiliary control box. The auxiliary control box is mounted in the corner of the unit under the side air hood that is next to the access door marked FILTER SECTION. To gain access to the aux- iliary box, remove the auxiliary control box cover. When re- placing the auxiliary control box cover, be sure to secure the cover properly in order to prevent water from being drawn into the auxiliary control box.

On 054-074 units, the inlet guide vane differential pressure switch is mounted on an upright located behind the evaporator- fan motor. See Fig. 43.

BELT INSTALLATION AND TENSIONING

IMPORTANT: When installing or replacing belts, al- ways 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.

1.Turn off unit power.

2.Adjust motor plate so belts can be installed without stretch- ing over the grooves of the pulley. (Forcing the belts can result in uneven belt stretching and a mismatched 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 (1/2-in. de¯ection with one ®nger) is obtained. Be sure to adjust both adjusting bolts the same number of turns.

NOTE: Check the tension at least twice during the ®rst day of operation, as there is normally a rapid decrease in tension until the belts have run in. Check tension periodically thereafter and keep it at the recommended tension.

With the correct belt tension, belts may slip and squeal momentarily on start-up. This slippage is normal and dis- appears after wheel reaches operating speed. Excessive belt tension shortens belt life and may cause bearing and shaft damage.

Fig. 44 Ð Motor Plate Adjustment

PULLEY ALIGNMENT Ð For proper belt life, the motor and fan pulleys must be properly aligned. To check, ®rst 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 ad- justing 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 ALTERNATE MOTOR PULLEY (Evapora- tor Fan Only) Ð On all units, the alternate motor pulley is ®eld-supplied. To install the alternate 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

1.Turn off unit power.

2.Remove fan guard and loosen fan hub setscrew.

3.See Fig. 32 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.

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