Carrier 90MA/MF/MU manual Service

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switch T-HIGH to energize liquid line solenoid (LLS) [to activate the full evaporator coil and all compressor cylinders]. If thermostat switch T-HIGH is not calling for cooling, power flows to energize compressor unloader solenoid (US) [to unload compressor cylinders].

When room temperature falls to the cutout point of T-LOW, switch T-LOW opens to de-energize CHR, stopping the compressor motor and energizing CH. The machine enters a stand-by state, ready to restart automatically on room thermostat call for cooling.

If any safety device opens (CLO, SPS, DPS, IP, OLA or, OLB) relay CHR is de-energized, stopping the compressor motor and energizing the crankcase heater.

TO PLACE THE UNIT IN THE HEAT MODE: The switch (SW) is placed in the HEAT position. With thermostat (T-LOW) calling for heating (closed to contacts R & B), 24 volt control power flows through manual reset temperature cutout MC to energize safety relay H2. Power also flows through air flow switch (AS) and automatic cutout (AC) to energize operating relay (H1). Energizing relays H1 and H2 closes contacts to energize the heaters.

Placing SW in the FAN position de-energizes all cooling or heating control circuits in the same manner as activation of a safety switch. Placing SW in the OFF position also de-energizes IFC to stop the indoor fan motor.

5.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

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

CAUTION

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

5.1Return--Air Grille Removal a. Pull grille out from top.

b. Pull grille up to release hinge pins from lower panel. c. To reassemble, reverse procedure.

5.2Access Panel Removal

a.Remove return-air grille as described above.

b.Remove the panel fastening screws now exposed.

c.Pull out and down to remove top panel.

d.Pull out and up to remove bottom panel.

5.3Evaporator Fan Adjustment

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.

SPEED ADJUSTMENT - The fan motor pulleys are factory set at the fan speeds listed in Table 1, Table 3 or Table 2. to change fan speed, do the following:

a. Shut off unit power supply.

b. Loosen fan belt by loosening fan motor from mount- ing bracket. Do not loosen fan motor mounting brack- et from unit.

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

d.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 or mo- tor full load amps indicated on motor nameplate.

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

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

g.Check fan operation. Repeat above procedure as re- quired.

Figure 8 Fan Pulley Adjustment

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).

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Contents Installation Operation & Service Models Safety Summary 62--10458--00 Safety-2 Table of Contents List of Illustrations Introduction Base Unit 90MA/MF/MU Units 404 406 408 Base Unit 90MA/MF Units Unit Dimensions Install water-regulating valve in water supply line Unit Length of RUN Operation Service Condensers may require cleaning of water-deposited scale Forced Circulation Method Refrigerant Charging 134a Units Mounting Wiring Schematic -- 90MA/MF/MU004/006 Component Arrangement -- 90MA/MF/MU004/006 62--10458--00 Wiring Schematic -- 90MA/MF/MU008/012 Component Arrangement -- 90MA/MF/MU008/012 62--10458--00 Index 62--10458--00

90MA/MF/MU specifications

The Carrier 90MA/MF/MU series represents a significant advancement in HVAC technology, designed for commercial applications needing reliability, efficiency, and precision in climate control. These units are renowned for their ability to cater to varying thermal loads while minimizing energy consumption, making them an ideal choice for various settings including offices, retail spaces, and industrial facilities.

One of the standout features of the Carrier 90MA/MF/MU series is its impressive energy efficiency. The equipment is designed with advanced thermodynamic principles to ensure maximum heat transfer and minimal energy loss. With high Seasonal Energy Efficiency Ratios (SEER) and Energy Efficiency Ratios (EER), these units help building owners achieve higher energy savings compared to traditional HVAC systems.

Another significant characteristic of the 90MA/MF/MU series is the integration of advanced control technologies. The units come equipped with sophisticated microprocessor-based controls that allow for precise temperature management and enhance overall system performance. Features like modulating capabilities and variable speed fans provide superior comfort levels by continuously adjusting to the changing environmental conditions.

The 90MA series also emphasizes quiet operation, which is critical for commercial environments. The innovative design includes insulation and vibration dampening technologies that reduce noise levels, ensuring a comfortable working atmosphere.

Durability and reliability are also central to the design of the Carrier 90MA/MF/MU series. These units are engineered with high-quality materials and components, including robust compressors and corrosion-resistant finishes that withstand harsh weather conditions. This durability extends the lifespan of the units, thus reducing maintenance costs and downtime.

In terms of versatility, the 90MA/MF/MU series offers a broad range of configurations and options, including various sizes and capacities. This flexibility allows for tailored solutions that meet the specific needs of different applications, from large commercial buildings to smaller retail outlets.

The series also supports environmentally friendly refrigerants that comply with global standards, marking Carrier’s commitment to sustainable practices. This approach not only reduces environmental impact but also positions businesses favorably in the eyes of eco-conscious consumers.

Overall, the Carrier 90MA/MF/MU series stands out as a pinnacle of efficiency, performance, and reliability in the commercial HVAC market. Its advanced technologies and thoughtful design cater to the diverse needs of modern businesses while promoting a sustainable and comfortable indoor environment.
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