McQuay MMC125B User Manual

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MDB - 2004

Ducted Split Systems

Models: MDB 075-750B

 MDB 125-150C

 MDB 075-500BR

 MDB 125CR

Questions and Answers:

F
fitzgeraldrebeccaAug 9, 2025
Why is my McQuay MMC125B not cooling properly?
- C
  Cheryl GreenAug 10, 2025
  If your McQuay Air Conditioner is running but not cooling effectively, several factors could be the cause. First, make sure the thermostat isn't set too high; try resetting it. Ensure all doors and windows are completely closed. If these steps don't help, there might be an obstruction blocking the unit's inlet or outlet; remove any objects you find. For issues such as a dirty condenser coil or insufficient refrigerant, it is best to contact your local dealer.
M
Mr. Joseph RodriguezAug 17, 2025
What to do if both fan and compressor on my McQuay MMC125B don't work?
- A
  Aaron BrockAug 17, 2025
  If neither the fan nor the compressor is working on your McQuay Air Conditioner, there are a few things you can check. First, there may be a power failure; the unit should resume operation when the power supply is restored. Also, the starter may have tripped; try resetting it. Finally, inspect the fuse in the power switch or operating unit and replace it if it's blown.
M
Michael JacksonAug 25, 2025
How to fix a McQuay MMC125B when the fan is not working?
- M
  Michael DawsonAug 26, 2025
  If the fan on your McQuay Air Conditioner isn't working, start by checking the power supply. If the power supply is fine, the issue might be a faulty fan capacitor or fan motor, in which case you should contact your local dealer. Another potential cause is a faulty switch, which would need to be changed.
A
amartinezAug 31, 2025
What to do if McQuay Air Conditioner fan works, but the compressor doesn't?
- M
  mckenziemeganAug 31, 2025
  If the fan on your McQuay Air Conditioner is working, but the compressor isn't, there are a few potential reasons. First, the thermostat setting might be too high; try resetting it. It's also possible that the dual pressure control has tripped; in this case, reset the pressure control. For compressor or compressor contractor issues, contact your local dealer.

McQuay MMC125B Specifications

General

Brand	McQuay
Model	MMC125B
Category	Air Conditioner
Language	English

Summary

General Specifications

Safety Controls

Lists safety controls like high/low pressure cut-outs and crankcase heaters.

Specifications

Heatpump

Cooling Only

Detailed technical specifications for cooling-only models.

Performance Characteristics

50Hz R22 Specifications

Performance data for cooling models at 50Hz with R22 refrigerant.

Cooling Model

Tables detailing cooling performance characteristics for various models.

Blower Performance Curves

MDB 075B Blower Performance Curve

Performance curves for the MDB 075B model's blower.

MDB 100B Blower Performance Curve

Performance curves for the MDB 100B model's blower.

MDB 125B Blower Performance Curve

Performance curves for the MDB 125B model's blower.

MDB 125C Blower Performance Curve

Performance curves for the MDB 125C model's blower.

MDB 150B Blower Performance Curve

Performance curves for the MDB 150B model's blower.

Wiring Diagrams (Cooling)

Model: MDB 075B – MMC 075C

Cooling wiring diagram for MDB 075B and MMC 075C models.

Wiring Diagrams (Heatpump)

Indoor (Export)

Heatpump indoor wiring diagrams for export models.

Model: MDB 125CR (Export)

Heatpump indoor wiring diagram for MDB 125CR export model.

Refrigerant Circuit Diagram

Model: MMC 075C/100C

Refrigerant circuit diagram for MMC 075C/100C models.

Installation (Indoor)

Installation (Outdoor)

Location For Installation Of The Condensing Units

Requirements for outdoor unit placement to ensure optimal cooling capacity.

Field Piping

Maximum Pipe Length And Maximum Number Of Bends

Guidelines on pipe length, bends, and elevation affecting performance.

Installation Clearance

A) For MMC – B/BR Series (Single/Multiple Condensing Unit)

Clearances for MMC B/BR series outdoor units when installed in groups.

B) For MMC – C/CR Series

Clearances for MMC C/CR series outdoor units.

Vacuuming And Charging

Vacuuming

Charging

System Refrigerant Charge Level Guidelines

Cooling Only

Guidelines for refrigerant charge levels for cooling-only models.

Additional Charge

Servicing And Maintenance

Maintenance

Recommendations for proper and regular maintenance for optimal performance.

Operation

Electrical Connection

Wiring regulations and precautions for electrical connections.

Sequential Controller

Troubleshooting

No Cooling

Insufficient Cooling

High Discharge Pressure

Low Discharge Pressure

High Suction Pressure

Low Suction Pressure

Noisy Operation

Related product manuals

McQuay MMC125BR

McQuay MMC100BR

McQuay MMC075CR

Preview: McQuay MWM-LW