Changing The Fan Speed; Aligning Blower And Motor Pulleys; Bearings; Motor - Carrier WeatherMaster 50HCQ04-12 Service And Maintenance Instructions

Changing the Fan Speed

1. Shut off unit power supply. Use proper lockout/tagout pro-
cedures.
2. Loosen belt by loosening fan motor mounting nuts. See
Fig. 8.
3. Loosen movable pulley flange setscrew. See Fig. 10.
4. Screw movable flange toward fixed flange to increase
speed and away from fixed flange to decrease speed.
Increasing fan speed increases load on motor. Do not
exceed the maximum specified speed.
5. Set movable flange at nearest keyway of pulley hub.
Tighten setscrew and torque to 65 to 70 in.-lb (7.4 to
7.9 Nm).

Aligning Blower and Motor Pulleys

1. Loosen blower pulley setscrews.
2. Slide blower pulley along blower shaft. Make angular
alignment by loosening motor mounting plate front and
rear bolts.
3. Tighten blower pulley setscrews and motor mounting
bolts. Torque bolts to 65 to 70 in.-lb (7.4 to 7.9 Nm).
4. Recheck belt tension.

Bearings

The fan system uses bearings featuring concentric split locking
collars. A Torx 1 T-25 socket head cap screw is used to tighten
the locking collars. Tighten the locking collar by holding it
tightly against the inner race of the bearing. Tighten the socket
head cap screw. Torque cap screw to 55 to 60 in.-lb (6.2 to
6.8 Nm). See Fig. 11. Check the condition of the motor pulley
for signs of wear. Glazing of the belt contact surfaces and ero-
sion on these surfaces are signs of improper belt tension and/or
belt slippage. Pulley replacement can be necessary.
Fig. 11 — Tightening Locking Collar

MOTOR

When replacing the motor, also replace the external-tooth lock
washer (star washer) under the motor mounting base; this is part
of the motor grounding system. Ensure the teeth on the lock
washer are in contact with the motor's painted base. Tighten mo-
tor mounting bolts and torque to 120 ± 12 in.-lbs (14 ± 1.4 Nm).
Change fan wheel speed by changing the fan pulley (larger
pitch diameter to reduce wheel speed, smaller pitch diameter to
increase wheel speed) or select a new system (both pulleys and
matching belt). The horsepower rating of the belt is primarily
dictated by the pitch diameter of the smaller pulley in the drive
system (typically the motor pulley in these units). Do not in-
stall a replacement motor pulley with a smaller pitch diameter
than was provided on the original factory pulley.
Before changing pulleys to increase fan wheel speed, check the
fan performance at the target speed and airflow rate to deter-
mine new motor loading (bhp). Use the fan performance tables
or use the Packaged Rooftop Builder software program. Con-
1. Torx is a registered trademark of Acument Intellectual Properties
LLC.
LOCKING COLLAR
T--- 25 TORX SOCKET
HEAD CAP SCREW
firm that the motor in this unit is capable of operating at the
new operating condition. Fan shaft loading increases dramati-
cally as wheel speed is increased.
To reduce vibration, replace the motor's adjustable pitch pulley
with a fixed pitch pulley (after the final airflow balance adjust-
ment). This will reduce the amount of vibration generated by
the motor/belt-drive system.

HEAT PUMP REFRIGERATION SYSTEM

UNIT OPERATION AND SAFETY HAZARD
Failure to follow this warning could cause personal injury,
death and/or equipment damage.
This system uses Puron
sures than R-22 and other refrigerants. No other refrigerant
may be used in this system. Gage set, hoses, and recovery
system must be designed to handle Puron refrigerant. If un-
sure about equipment, consult the equipment manufacturer.

Outdoor Coil

The 50HCQ outdoor coil is fabricated with round tube copper
hairpins and plate fins of various materials and/or coatings (see
"Appendix I — Model Number Significance" to identify the
materials provided in this unit). All unit sizes use composite-
type two-row coils. Composite two-row coils are two single-
row coils fabricated with a single return bend end tubesheet.

Indoor Coil

The indoor coil is traditional round-tube, plate-fin technology.
Tube and fin construction is of various optional materials and
coatings (see Appendix A — Model Number Nomenclature on
page 39). Coils are multiple-row.
Recommended Outdoor Coil Maintenance and
Cleaning
Routine cleaning of coil surfaces is essential to maintain proper
operation of the unit. Elimination of contamination and remov-
al of harmful residues will greatly increase the life of the coil
and extend the life of the unit. The following maintenance and
cleaning procedures are recommended as part of the routine
maintenance activities to extend the life of the coil.
REMOVE SURFACE LOADED FIBERS
Surface loaded fibers or dirt should be removed with a vacuum
cleaner. If a vacuum cleaner is not available, a soft non-metal-
lic bristle brush may be used. In either case, the tool should be
applied in the direction of the fins. Coil surfaces can be easily
damaged (fin edges can be easily bent over and damage to the
coating of a protected coil) if the tool is applied across the fins.
NOTE: Use of a water stream, such as a garden hose, against a
surface loaded coil will drive the fibers and dirt into the coil. This
will make cleaning efforts more difficult. Surface loaded fibers
must be completely removed prior to using low velocity clean wa-
ter rinse.
PERIODIC CLEAN WATER RINSE
A periodic clean water rinse is very beneficial for coils that are
applied in coastal or industrial environments. However, it is
very important that the water rinse is made with a very low ve-
locity water stream to avoid damaging the fin edges. Monthly
cleaning as described below is recommended.
Ensure clearances are in accordance with local installation
codes, the requirements of the gas supplier and the manu-
facturer's installation Instructions.
8
WARNING
® refrigerant which has higher pres-
CAUTION