Panasonic U-72MF2U9 Service Manual page 85

8. Pumping Out Refrigerant from Outdoor Unit
8. Pumping Out Refrigerant from Outdoor Unit
8-2. If Remote Controller is Not Available for maintenance of Outdoor Unit
(1) See "3. Backup Operation" and perform backup operation.
(2) Connect the manifold gauge valves at the Lo side to the low-pressure outlet port of the outdoor unit to be
repaired. Also connect the refrigerant recovery cylinder to any one of the normal outdoor units at the liquid line
service port (Schrader-type push-to-release valve). Perform the connection work quickly so that no air is
allowed to enter. (Fig. 15)
* Connecting the refrigerant recovery cylinder is done to prevent pressure from rising excessively during the
backup operation by recovering the refrigerant from the outdoor unit to be repaired.
(Measure the weight of the refrigerant and cylinder itself beforehand and provide sufficient safety measures,
such as installing a high-pressure cutout in the circuit.)
The hoses may be subject to internal pressure from the refrigerant inside the outdoor
unit. Check that the manifold gauge valves are fully closed beforehand.
CAUTION
A Schrader-type push-to-release valve is provided at each connection port.
(3) Determine the outdoor unit where the unit No. setting (SW5)(3P DIP switch)(BLU) on the outdoor unit control
PCB is set to No.1.
(4) Short-circuit the MODE pin ("COOL" side of CN40) on the outdoor unit control PCB of the No. 1 unit.
* Switching of the 4-way valve occurs immediately before operation starts. Therefore it does not change at this
time. (Mode change cannot be judged from the sound.)
(5) Short-circuit the CHK pin (CN23) to start operation, leave the unit running for a while. Touch the suction tube,
discharge tube with fingers to determine whether the unit is running in cooling mode.
Low-pressure outlet port
(for ø5/16" (ø7.94m)-
dia connector)
Manifold
gauge
Lo Hi
High-pressure
outlet port (for
ø5/16" (ø7.94mm) -
dia connector)
Connect from here to
refrigerant recovery unit
Faulty outdoor unit
2 - 21
Outdoor Unit Repair Procedures
Outdoor Unit Repair Procedures
Other outdoor unit
2WAY VRF SYSTEM
3WAY VRF SYSTEM
Liquid tube service port
(for ø5/16" (ø7.94mm)-
dia connector)
Refrigerant
recovery
cylinder
Measuring scale
To indoor unit
Fig. 15
1
2
3
4
5
6
7
8
9