Vertiv Liebert Mini-Mate MT036, Installer/User Manual, Page: 45 / 80

9.5.2 Condensate Pump
WARNING! Risk of electric shock. Can cause injury or death. Open all local and remote electric
power-supply disconnect switches and verify that power is Off with a voltmeter before working
within the condensate pump electrical connection enclosure. The Liebert® iCOM™ does not
isolate power from the unit, even in the “Unit Off” mode. Some internal components require and
receive power even during the “Unit Off” mode of the Liebert® iCOM.
To maintain the condensate pump:
1. Disconnect power to the unit using the disconnect switch.
2. Check for and clear obstructions in gravity lines leading to the condensate pump.
3. Remove the sump, clean with a stiff nylon brush and flush with water.
4. Inspect and clear clogs in the discharge check valve and float mechanism.
5. Reassemble and check for leaks.
9.6 Electric Reheat Maintenance
• Inspect and clean reheat elements.
• Inspect and tighten support hardware.
9.7 Thermostatic Expansion Valve (TXV) Maintenance
The TXV performs one function: It keeps the evaporator supplied with enough refrigerant to satisfy load
conditions. It does not affect compressor operation.
Proper valve operation can be determined by measuring superheat. The correct superheat setting is
between 10 and 15°F (5.6 and 8.3°C). If too little refrigerant is being fed to the evaporator, the superheat
will be high. If too much refrigerant is being supplied, the superheat will be low.
9.7.1 Determining Suction Superheat
To determine superheat:
1. Measure the temperature of the suction line at the point the TXV bulb is clamped.
2. Obtain the gauge pressure at the compressor suction valve.
3. Add the estimated pressure drop between the bulb’s location and the suction valve.
4. Convert the sum of the two pressures to the equivalent temperature.
5. Subtract this temperature from the actual suction line temperature. The difference is
superheat.
9.7.2 Adjusting Superheat Setting with the TXV
To adjust the superheat setting:
1. Remove the valve cap at the bottom of the valve.
2. Turn the adjusting stem counterclockwise to lower the superheat.
3. Turn the adjusting stem clockwise to increase the superheat.
NOTE: Make no more than one turn of the stem at a time. Allow up to 15 minutes of fully loaded
compressor operation before checking superheat or making additional stem adjustments.
9 Maintenance 45