Panasonic CS-S9TKV Service Manual page 68

11.3.6 Pump Down Method When Reuse Existing Piping (R22 Model) for R410A Model
Compressor oil of R22 model is insoluble in compressor oil of R410A model.
The mixing of compressor oil may cause damage of compressor.
Possibility of Mixing
 Reuse of piping of R22 model is dangerous because of its
compressor oil.
 Reuse the piping of R22 model only when it is unavoidable, eg.
concealed piping.
 When reuse piping of R22 model, pump down must be carried out
properly to ensure compressor oil which is remained inside piping is
collected away.
11.3.7 Proper pump down method
1 Operate air conditioner
at cooling mode for
10~15 minutes.
Most Important Process
Purpose: To make the oil
& refrigerant mix together.
They are in separated
condition when
air conditioner
is stopped.
In case pump down cannot be done, please flush the piping using R410A refrigerant.
2 After 10~15 minutes of pre operation,
close 2 way valve. After 3 minutes,
close 3 way valve.
Mixed refrigerant & oil
will be collected into
outdoor unit.
To Reuse Old Piping
 Piping of R22 model can be reused only when air conditioner is
properly pumped down.
 The purpose of pump down is to collect back the compressor oil
(which is mixed with refrigerant and circulating inside refrigeration
cycle) properly into the outdoor unit of air conditioner.
3 Take out air conditioner
unit.
Only very small
amount of oil remain
inside piping, which is
acceptable.
68
4 Install New Refrigerant air
conditioner.