Precautions When Reusing Existing R22 Refrigerant Pipes; Connecting A New Air Conditioner To Existing R22 Refrigerant Pipes - Mitsubishi Electric PUHZ-RP250YHA2 Service Manual

2-3. Precautions when reusing existing R22 refrigerant pipes

(1) Flowchart
The existing pipe thickness meets specifi-
cations and the pipes are not damaged.
Check if the existing air conditioner can operate.
The existing air conditioner can operate.
After operating the cooling system for about
30 minutes, do a pump down work.
Disconnect the existing air conditioner from
the pipes.
The existing piping can be reused.
After flaring the pipes again, connect the
new air conditioner.
Perform the following inspections: air
tightness test, vacuum dryness (additional
refrigerant charge), gas leakage check
Replacement operation
Test operation

Connecting a new air conditioner to existing R22 refrigerant pipes

Flare the pipe for the use with R410A refrigerant.
Use the flare nut attached to indoor and outdoor unit of the new air conditioner only.
When reusing existing R22 refrigerant pipes of which gas pipe is 28.58mm and, when the outdoor unit is installed to lower
position than the indoor unit, be sure to change the setting of the DIP SW8-1 on the controller circuit board of the outdoor
unit to ON.
This is to increase the speed of refrigerant passing in the gas pipe so that refrigerant oil can smoothly flow in the system.
• Use a different-diameter joint or brazing for the connection.
When reusing standard-size existing R22 refrigerant pipes.
The pipes can be reused with pipe length restriction described on TECHNICAL DATA BOOK.
Measure the existing pipe thickness and check
for damage.
The existing air conditioner cannot operate.
Use a refrigerant recovery device to recover the refrigerant.
Check the oil condition when recovering refrigerant.
Oil is clean. (Clear to brownish color)
In case that existing pipes were
used for gas or oil heat pump
system, be sure to clean the pipes.
·When performing replacement operation, make sure that DIP SW8-2 on outdoor unit controller board is
set to ON.
Chemical compounds containing chlorine left in existing pipes are recovered by replace filter.
The air conditioner automatically performs cooling operation through replace filter for about 2 hours.
5
The existing pipe thickness does not meet
specifications or the pipes are damaged.
Oil is dirty. (Black color)
When the compressor bearings
are seized, winding is damaged
or the compressor breaks down,
iron particles or oil deterioration will
blacken the oil.
The existing pipes cannot be reused.
Use new pipes.