Fisher FS2MIF-141AE2 Service Manual page 15

● Refrigerant pipe diameter is different according to indoor unit to be connected. When using the
extension pipe, refer to the tables below.
● When refrigerant pipe diameter is different from that of outdoor unit union (for 18K indoor unit), additional
transfer connector needs to be used on outdoor unit union.
Indoor unit
Model
7K9K12K
18K
24K
Outdoor unit union diameter (mm/inch)
Indoor unit A/B/C/D/E
7.4 Installation for the first time
Air and moisture in the refrigerant system have undesirable effects as below:
● Pressure in the system rises.
● Operating current rises.
● Cooling or heating efficiency drops.
● Moisture in the refrigerant circuit may freeze and block capillary tubing.
● Water may lead to corrosion of parts in the refrigerant system.
Therefore, the indoor units and the pipes between indoor and outdoor units must be leak tested and
evacuated to remove gas and moisture from the system.
Gas leak check (Soap water method):
Apply soap water or a liquid neutral detergent on the indoor unit connections or outdoor unit
connections by a soft brush to check for leakage of the connecting points of the piping. If bubbles come out,
the pipes have leakage.
Pipe diameter (mm/inch)
Liquid 6.35(1/4)
Gas 9.52(3/8)
Liquid 6.35(1/4)
Gas 12.7(1/2)
Liquid 9.52(3/8)
Gas 15.9(5/8)
Extension pipe diameter (mm/inch)
Liquid
Gas
Liquid
Gas
Liquid
Gas
Liquid
Gas
-15-
6.35(1/4)
9.52(3/8)
6.35(1/4)
12.7(1/2)
9.52(3/8)
15.9(5/8)
6.35(1/4)
9.52(3/8)
12.7(1/2)