Lennox FLATAIR FMC-H Installation, Operating And Maintanance Manual page 26

4.- MAINTENANCE
4.2.- CORRECTIVE MAINTENANCE
- Take very special care if 4-way or check valves are to be replaced since these have internal components that are very heat-sensitive such as
plastic, teflon, etc.
- If a compressor is to be replaced, disconnect it electrically and un-braze the suction and discharge lines. Remove the securing
screws and replace the old compressor with the new one. Check that the new compressor has the correct oil charge, screw it to
the base and connect the lines and electrical connections.
- Evacuate above and below through the Schrader valves of the outdoor unit until -750 mm Hg is reached.
Once this level of vacuum has been reached, keep the pump running for at least one hour.
DO NOT USE THE COMPRESSOR AS A VACUUM PUMP.
- Charge the unit with refrigerant according to the data on the Rating Plate for the unit and check that there are no leaks.
PRECAUTIONS TO BE TAKEN WHEN USING OF R-410A Refrigerant:
R-40A refrigerant is used in the unit; the following standard precautions for this gas should therefore be taken:
- The Vacuum Pump must have a Check Valve or Solenoid Valve fitted.
- Pressure Gauges and Hoses for exclusive use with R-40A Refrigerant should be used.
- Charging should be carried out in the Liquid Phase.
- Always use scales to weigh-in charge
- Use the Leak Detector exclusive for R-40A Refrigerant.
- Do not use mineral oil, only synthetic oil to ream, expand or make connections.
- Keep pipes wrapped before using them and be very thorough about any possible dirt (dust, filings, burrs, etc.).
- When there is a leak, collect what remains of the charge, create a vacuum in the unit and completely recharge with new R-
40A Refrigerant.
- Brazing should always be carried out in a nitrogen atmosphere.
- Reamers should always be well sharpened.
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