Carrier 90MU, 90MA specifications Service, Return-AirGrille Removal, Fan Pulley Adjustment

SERVICE

WARNING

NEVER reach into unit while fan is running. LOCK OPEN AND TAG unit disconnect before working on fan. Remove fuses and take them with you after noting this on tag.

CAUTION

1.Sharp edges of coil fins are exposed. To prevent injury, cover top of evaporator with cardboard or a few layers of heavy tape.

2.To avoid coil damage, cover evaporator face with plywood or other rigid sheet material. If any coil fins are mashed or bent, straighten with a coil fin comb of the proper tooth spacing (refer to “coil fins/inch” in Table 1). Check for refrigerant leaks.

Return-Air Grille Removal

1.Pull grille out from top.

2.Pull grille up to release hinge pins from lower panel.

3.To reassemble, reverse procedure.

Access Panel Removal - Remove return-air grille as described above.

Remove the panel fastening screws now exposed. TOP PANEL - Pull out and down.

BOTTOM - Pull out and up.

Evaporator Fan Adjustment - Observe fan compartment Caution note above. The fan motor pulleys are factory set at the fan speeds listed in Table 1.

TO CHANGE FAN SPEED

1.Shut off unit power supply.

2.Loosen fan belt by loosening fan motor from mounting bracket. Do not loosen fan motor mounting bracket from unit.

3.Loosen movable pulley flange set screw (Figure. 8).

4.Screw movable flange toward fixed flange to increase fan speed and away from fixed flange to decrease speed. Increasing fan speed increases load on motor. Do not exceed maximum allowable fan speed (Tables 1A/B/C/2A/B/C) or motor full load amps indicated on motor nameplate.

5.Set movable flange set screw at nearest flat of pulley hub and tighten set screw.

FIGURE 8 - FAN PULLEY ADJUSTMENT

6.Check pulley alignment and belt tension adjustment as described below.

7.Check fan operation. Repeat above procedure as required.

PULLEY ALIGNMENT - Shut off unit power supply. Loosen fan motor pulley set screws and slide fan pulley along fan shaft. Make angular alignment by loosening motor from mounting bracket (See Figure. 8).

BELT TENSION ADJUSTMENT - Shut off unit power supply. Loosen fan motor from mounting bracket. Do not loosen motor mounting bracket from unit. Move fan motor up or down until proper belt tension is achieved (approxi- mately 3/4-in. deflection with 8-pound tension at midpoint of belt span).

Lubrication - Fan motor and fan shaft bearings are lubricated for the life of the bearings. No re-lubrication is required

Return-Air Filters - Inspect filters twice monthly and clean as required by operating conditions. Filter size and type are listed in Tables 1A/B/C/2A/B/C. To clean filters flush with hot water or steam or soak in a mild water solution of soap or detergent. Refer to filter manufacturer's instructions as applicable.

Do not operate unit without return-air filters in place.

Condensate Drains - Clean the drain line and unit drain pan at the start of each cooling season. Check flow by pouring water into drain. Be sure trap is filled as shown in Figure. 7 to maintain an air seal.

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations

Printed in U.S.A. Pg 13 90MA-3SI SUPERCEDES FORM 62-02971-00 09-2009