Liebert Mini-Mate2 MMD24E User Manual page 7

2 & 3 tons, 50 & 60hz

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User manual (72 pages)

Table of Contents

System configurations - 60Hz. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Table 2

System configurations - 50Hz. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Table 3

Application limits, evaporator and chilled water units* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Table 4

Application limits, indoor and outdoor air-cooled condensing units . . . . . . . . . . . . . . . . . . . . . . . 13

Table 5

Application limits, indoor water/glycol-cooled condensing units . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Table 6

Ceiling unit weights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Table 7

Cooling unit air flow at 0.3 IWG (75PA) ESP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Table 8

Recommended refrigerant line sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Table 9

Pipe length and condenser elevation relative to evaporator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Table 10

Line charges - refrigerant per 100 ft. (30m) of Type L copper tube . . . . . . . . . . . . . . . . . . . . . . . . 22

Table 11

Refrigerant charge in Liebert pre-charged R-407C line sets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Table 12

Equivalent lengths for various pipe fittings, ft (m). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Table 13

Refrigerant charge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Table 14

Connection sizes and torque . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Table 15

Net weights-evaporator and chilled water units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Table 16

Net weight, high static blower module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Table 17

Indoor condensing unit airflow, CFM at 0.5 iwg esp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Table 18

Centrifugal condenser dimensions, weights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Table 19

Dimensions and net weights-air-cooled outdoor condensing units . . . . . . . . . . . . . . . . . . . . . . . 35

Table 20

Net weight, indoor water/glycol-cooled condensing unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Table 21

View default setpoints and allowable ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Table 22

Microprocessor night and weekend setback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Table 23

Setup functions, default values and allowable ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Table 24

Alarm default time delays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Table 25

Switch settings (wall box board) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Table 26

Equipment switch settings (unit control board) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Table 27

Cooling and dehumidification load response of hot gas bypass . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Table 28

External static pressure available . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Table 29

Typical discharge pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Table 30

DIP switch settings for humidifier control board (2- and 3-ton unit . . . . . . . . . . . . . . . . . . . . . . . 65

Table 31

Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

TABLES

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Troubleshooting

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Do you have a question about the Mini-Mate2 MMD24E and is the answer not in the manual?

Questions and answers

george felix

January 29, 2025

Low suction & head pressure w/ glycol system & free cooling. Inlet cooling water 56 degrees, 10# diff. press, recovered refrigerant & weighed in proper charge 96oz.

1 comments:

Mr. Anderson

February 10, 2025

Low suction and head pressure in a Liebert Mini-Mate2 MMD24E with a glycol system and free cooling could be caused by:

1. Low Glycol Solution Level – Insufficient glycol in the system can reduce heat transfer efficiency.
2. Improper Glycol Concentration – Incorrect glycol mixture can affect system performance.
3. Low Water/Glycol Temperature – If the temperature is too low, the free-cooling coil may take over, reducing suction and head pressure.
4. Restricted Flow in the System – Blockages or closed valves in the glycol piping can limit circulation.
5. Malfunctioning Three-Way Valve – If the free-cooling valve does not function correctly, it may divert flow improperly.
6. Dirty or Clogged Coil – A buildup of debris on the free-cooling coil can restrict heat exchange.
7. Air in the System – Entrapped air can reduce efficiency and cause pressure issues.
8. Pump Issues – A faulty or improperly sized pump may not circulate glycol effectively.

Checking glycol levels, valve operation, and system cleanliness can help diagnose the issue.